Anyway everything I said becomes quite absolute after doing some math:

I calculated 3 specs: 10/48/3, 40/18/3 and 33/28 all for maxed DPS (no range for the arcane specs since you're in 30 yards anyway and getting more range on fire requires gimping DPS and/or DPM unlike with the 10/48/3 spec).
Spell damage was 1250 for all, int 500, crit on character screen was 30% for 10/48/3 (and calculated based on that the crit with 40/18/3 and 33/28).
For hit values, I did the math and needed to estimate the amount of spell damage you could gain by reducing your hit rating due to extra hit talents and assumed your hit with arcane spells is always maxed. I noticed that it's still worth keeping capped hit rating if the spell damage you can get per lost hit rating on items is a bit under 1 point per point, and I estimate the value in practice to be around 0.7, therefore hit rating is worth keeping at max with all specs. However 33/28 doesn't have elemental precision, and therefore needs more hit rating - so I deducted the appropriate spell damage at 0.7 spell damage per hit rating needed to get capped.
For AP I calculated as if you keep using the same rotation (as if you let arcane spec ever spam AB it will obviously win and no point in calculating anything, just pick arcane if AB spamming is possible at any point of the fight), I multiplied all spells dps and mana cost by 1.025 as well as adding 1 APed pyro and removing 1 APed scorch every 3 minutes.
Combustion was estimated as a 2.5% DPS increase as it's almost impossible to calculate.

Results are as follows:

10/48/3
Fireball spam: 1254 DPS, 10.5 DPM
8XFireball+1XScorch: 1242 DPS, 10.6 DPM
Any other rotation has too low DPS to mention.

40/18/3
3XAB+2Xfireball+scorch: 1305 DPS, 8.4 DPM
Any other rotation has too low DPS to mention.

33/28
3XAB+2XFireball+Scorch: 1324 DPS, 8.8 DPM
2XAB+2Xfireball+Scorch: 1269 DPS, 10.3 DPM
Fireball spam: 1260 DPS, 9.9 DPM
8XFireball+1XScorch: 1255 DPS 10.1 DPM
any other rotation has too low DPS to mention.

As you can see 33/28 comes on top in everything other than the range loss and slight-medium DPM loss depending on the rotation. Most efficient rotation that still does more DPS than the best of 10/48/3 is very little behind it in DPM.

What this really relies on: perfect usage of AB rotations so you never get the max mana cost and never get the max casting time, 2/5 T5 and never losing the scorch debuff stacking (you can easily swap the first 2 fireballs for scroches which is neglicible DPS loss if done once in the fight, but if you have to do it multiple times your DPS *WILL* drop noticeably as scorch is much weaker - notice I didn't include scorch spam DPS for that reason).

Other things to note:
-AP PoM pyro really tips the tides here (see my old calculations a few posts up). I did take into account the GCD it takes and the one less APed scorch you have. Granted it's still kinda rough but pretty damn close to reality.
-Increasing crit rate significantly (to 40% in the 10/48/3 spec and proportional increase for the rest) does NOT significantly tip the scales for the 33/28 spec. The fireball spam DPS increases by ~1.5% or so, but the best rotation of ABX3+FireballX2+Scorch actually LOSES ~0.2% DPS (does 5.34% more DPS than 10/48/3 compared to the 5.55% extra DPS it would do with 30% crit).
General scaling of specs: 10/48/3 scales faster with both spell damage and crit, but so slightly better than even by increasing crit and +damage by a huge amount 33/28 3XAB+2XFireball+Scorch still win by over 5%.
-Arcane spec gives 15% regen while casting - while not much considering the DPM is lower anyway, when you use the *almost-the-same* rotation DPS/DPM-wise it might be enough to make it more DPM on top of making it more DPS.
-Best bracers in the game until alar are "of fiery wrath" so if you want arcane you're forced to lose spell damage by using bands of nefarious deeds, but then again there's the new BoE epic that's slightly better than "of fiery wrath" anyway so I'll probably by that when I feel I'm anywhere near 2/5 T5 and speccing 33/28. For now, since it's nearly the same DPS and less DPM (not using AB due to no 2/5 T5) I'll keep the range of 10/48/3.

I need to give it a try and see I guess, thought it would be possible considering you have 0.5s to play with. Using AM can really tune down the DPS as it's the only possible way to get >=6.5s casting between ABs without going above 8. Only possible rotations are AB+scorch, 2xfireball+scorch and 3xfrostbolt. If lag is too much for you to lose more than 0.5s every 3 spells it may screw over the whole spec, then again if you lose 0.5s over 2 spells you could ABX2-fireballX2 and still cast the AB so it's finishing casting right after the debuff wears off... But I doubt you get that much delay when using /stopcasting appropriately.
Dunno how quartz works, I just time my /stopcasting according to the latency to which I got used to, or even by knowing how long it takes a fireball to cast and hitting the fireball macro exactly 3 seconds after I hit the last one. Again I'll try do some testing to see how much time you really lose.

I can't. I just use(d) 2xFireball, 1xFireball+2xScorch or 4xScorch.

It took extreme effort, but I pulled it off. It requires completely perfect use of your /stopcasting and looking at nothing but your casting bar, but after a little practice I managed to pull it off a few times. Then again if you can't pull a scorch off and the AB that comes in its place doesn't need to be waited for, you lose similar DPS to what you would lose with any other spec without optimal use of /stopcasting.
Assuming you should learn to use /stopcasting perfectly anyway, the basic ABX3+fireballX2+scorch rotation still stands as the best DPS rotation. It just takes a lot of practice to master, especially in the heat of battle, I don't even wanna imagine how's that like with my 400 ping. But it's definitely very doable. And if you lose more than 0.5s between the 3rd AB to the next 1st AB, you can just do 3XAB+2Xfireball and your average DPS per time actually cating will actually increase, however your overall DPS will drop simply because you're wasting more time not casting anything, but that would be true for any spec when not using /stopcasting.
The thing about the 33/28 (or 40/18/3 although inferior) 3XAB+2Xfireball+scorch is that while it's doable, if you try it and mess up you lose a lot of DPS. Other specs you just lose the time wasted between casts. At that point it's impossible to calculate as the difference relies on your ability to keep up the rotation, not how good the rotation actually is.

Hopefully someday blizzard fixes all this dead time between casts due to latency issue and just let us que the next spell ahead of time and end this bullshit. My spells are designed and balanced to hit every 3 seconds, not 3 seconds + ping or 3 seoncds + your messup time with /stopcasting, which is total BS as it varies between people. I wonder how mages would fair in DPS if you could actually get every 3s spell casted with a 1/3s frequency...
Wishful thinking I guess, over 2.5 years of WoW and still nothing to adress this.

It uses the old, broke-ass 15 seconds =p.

3x frostbolt is easy, the trick is you need a stopcast for arcane blast coming in too. That will shave off the last fraction of a second you need to comfortably do frostboltx3 in the cycle.

Theoretically doing less interlude and more arcane blast is always good. However what's missing from that is that increasing your overall cast speed is a much more dramatic effect than just increasing your AB to interlude ratio. If you can cram more spells in the interlude you probably should, as it usually just means you're casting more spells overall.

Sorry I forgot about the T6. Remember that the trinket effects menu is only modeling the proc/use effects, it does NOT include passive stats. Mark of Defiance wasn't modeled because its proc is fairly ineffectual, and almost any of those listed trinkets would be a better use of the slot.

Also, apologies for the gear selector not being updated, I didn't make that section (Kalman did =p and he doesn't play a mage anymore). If someone would like to do the honors and update it, send that to me and I will happily include it in an immediate release and credit you for it.

Interlude has a minimum of 1.5s of flex (more if you're doing fewer AB). Imo, you're better served flexing down to 6s rather than up to 7.5

clearly something like one AM in 7.5s is a bad idea.

Right, but due to casting times being the same or longer, doing anything but the maximum possible number of spells will force you to reduce your casting speed, which is always bad.

I started going trough gear in the spreadsheet and I'm hoping to finish it sometime today.

Wowhead has been down for who knows how long... God I hate using Thottbot already over half year of fancy ajax tricks.

I've gone trough heads, necks, shoulders, backs and added the new rare hit gems.

Anyone have the updated spreadsheet with the additions recently made?

I also did the same 33/28 vs 10/48/3 comparison only if you have some latency even after you use /stopcasting.
I added different values of latency and changed the 3XAB-2Xfireball-scorch rotation to 3XAB-2Xfireball only, assuming your latency is big enough for you to lose at least 0.5s between the last AB of the rotation to the first AB of the next rotation (so you get more than 3+3+0.5=6.5). Added same delay between fireballs (I actually had 1 cell where I enter latency and it "fixes" the sheet, again with the assumption the rotation is working and you're not getting less than 0.5s lost total between ABs).

Results were 33/28 still wins by roughly the same amount (actually by a little more but it's a meaningless difference), so 33/28 with 2/5 T5 you win with either 0 latency and getting your 3XAB-2Xfireball-scorch rotation going or having some latency and having latency to the point where you can't get the scorch off but removing scorch won't get you using AB too early.

Then I went on and compared if you do have exactly the same amount of latency as I estimate that I get when I barely miss the scorch/AB, and still be too early on the scorch, and if I assume I wait just enough for the AB debuff to have 1.5s left 33/28 still comes on top. Now if you start reducing the latency all the way to 0 while still using the rotation in which you wait for the AB debuff, meaning you wait up to 1.5s per rotation, 33/28 still comes on top but the difference is only a little more than 1/2 of what it was in all other calculations. So even in the worst case scenario where you use a rotation that fits latency and you have no latency in reality (which is REALLY a "worst case" scenario that'll never really happen, meaning it'll always be better than this), 33/28 still does 2.6% more DPS.

So in the end AB spam spec with 2/5 T5 will pretty much always be the superior DPS and superior threat reduction while having reduced range and a little reduced mana efficiency, with an ability to put a lot of lot of pain in those rare short fights where you can AB spam or in those fights where AP PoM pyro AB spam makes even more of a difference.

got my shoulders, can't wait until we get more into SSC for the pants, but we're moving so slow... And I do also need the headpiece from void reaver (as vashj is still far) for the T5 pants to not be a spell damage decrease due to losing the spellstrike set bonus.