Can you post your modified spreadsheet? Nothing I'm doing on leulier's 2.4 spreadsheet will make Incinerate come ahead of Shadowbolt. I even modified my ISB talent points to 4/5 and set myself up as the only shadow user in the raid ISB tab to simulate the ISB nerf from the "fake" patch notes, and my DPS went up.

Unless you'll be running with more than 1 fire lock on the same target, having to refresh immolate befoer the last tick needs to be taken into account when calculating dps. If you're running multiple warlocks, though, that effect is greatly reduced but there's still a small chance for an incinerate to land without an immolate being up if you rely on the other warlock to cover your immolate dot-gap.

Don't have a place to upload things, but:
Go to the Lists tab and in every entry for Incinerate replace 2.5 with:
(2.5/(1+0.02*ember))

Check the raid debuffs for Imp Scorch and CoE/misery. Choose Imp as pet, 5 pts in emberstorm, 5 in imp immo and put immo in the casting list. I have CSD and t6 on in that version. With this as the stats:
Add shad 1,701.81
Add fire 1,647.81
Total crit % 32.64
Hit % from gear 16.00
Stamina 600
Intellect 671.33
Haste % 21.97
mp5 161.9798
HP 9000
Mana 10069.95

I might have made a mistake, but don't think I did... Let me know if that works out on yours.

The affliction lock is probably casting as well. Even so, the "haste" of the fire build would make the dot uptime pretty easy. Choosing between life tap or a close to 2s cast nuke means it'd be pretty easy to line it up. The probability of the gaps overlapping would be a pretty small dps loss.

In fact, if you actually need the liftap mana (which I would guess is reasonable but need to do the numbers to make sure) you could completely eliminate the dot-gap effect I mentioned even as a single lock if you just lifetap once when you know your next incinerate will fire up after your immolate wears off - then you can recast immolate without clipping.
The only way this would not work is if you had enough mana/regen for the fight duration to not need to lifetap every immolate.

I editted as you said.

In my original copy of the spreadsheet (for SB comparison), my stats are:

Shadow: 1726
Fire: 1609
Crit: 32%
Hit: 16%
Haste: 7.23%
mp5: 411.7 (accounting conservatively for VT and super mana pots)
HP: 10507
MP: 9388
custom lifetap OOM time: 360 seconds

In the second copy which has the Incinerate edit, to account for changing my cloak and weapon enchant, I changed:

Shadow: 1651
Fire: 1701
Crit: 33.13%

I'm getting 2289.31 for a Shadowbolt spamming build and 2081.34 for Incinerate with 5/5 Emberstorm and 5/5 Improved Immolate.

EDIT: Nevermind, forgot to turn on Improved Scorch. I thought it was turned on by default. Getting 2393.55 with the new Emberstorm.

Doh, that was testing out using a ton of the haste gear... Sounds like I didn't miscalc though, just had to get that 15% scorch buff. Again it's not a HUGE dps increase from shadow, but it is definitely an increase.

A quick sideways jump from the Fire-spec discussion.

My guild is currently working on Bloodboil in BT. We have cleared MH. I've been Demo for a long time but the fights seem so unfriendly for a pet. Destruction is definitely not working for me.

Can I get some advice regarding a spec for the rest of the bosses in BT?

Well, I mean, you could be the guild's affliction bitch, but aside from that, what real options do you have?

I guess I will just stay as destro and eventually I'll get items that'll make the spec shine. And in the meantime I'll gather +fire dmg items, just in case.

Anyone been doing any thinking regarding taking out Neltharions Tear from the bank again in SW? Might be an item to take into consideration for even the balance out, before getting your hands on the hit-gear that will be needed to maintain hitcap when taking the first couple of upgrades in SW.

T6 Belt - 20
T6 Boots - 28
Head: Illidan head - 21+14
Rings: Captured Storms and JC crafted - 38
T6 Shoulders(seems best for 4 part bonus) - 21
Nethervoid cloak - 18
---
160 hit

And there's plenty of room to play with still

Yeah, it would depend on how many SPs are in a typical raid. We usually have just one SP and 3-4 locks, so the DPS increase wouldn't have to be as large to make it worth the swap. When you did the quick math in the quoted post did you include 1 affliction lock or are all of your locks destro at this point? One affliction lock working against 2 SPs shows ~30% isb uptime.

You can definitely "shine" in t5/badge gear if your guild is still working through BT. I'd look into other reasons for lack of DPS than the gear.

It seems like [Eye of Magtheridon] is not mentioned that much anymore but I have a question. Is it still good enough to be worn if I am hit capped? Or just wear Icon + Crusade (at 16% hit)? My friend keeps telling me that I should drop my spellhit% from 16% down to 12% according to the DPS trinket website(sorry, can't remember the website's name) if i want to keep using Mag's eye.

Some say even if I am using Mag's eye i have to get 16% spellhit and others say I have to drop down to 12%. >.< I am confused. Currently my hit is 203. I am 1/45/15. I am also using icon + mag's eye for now and swap out icon with VST if the boss has AoE skills.

No, the new shoulders released off Eredar Twins are far superior to T6 shoulders. Given current known gear, if you aren't an engineer, t6 helm is the best in slot of the old pieces.

You also want to use the Skull of Guldan in these calculations.

Gimping your hit to 12% will result in a far greater DPS loss than the gain that the mag's eye proc will give you. Use Icon + Crusade.

I forgot to mention that i don't have crusade atm. I currently have Icon and Mag's eye(DPS trinkets that i have so far). So i take it that you meant I should just stay at 16%spellhit even if I am using Icon + Mag's eye?

Thanks in advance.

All Destruction Warlocks. I'm around 32% crit raid buffed (I'm in an elemental shaman group), our other long-time raiding Warlock is at about 30%, and our newest app is at something like 35% last I checked.

If there were a significant DPS increase from going to Fire, it would still be worth having one shadow to buff the SPs and their VT. Whether that's in the form of Affliction or Destro is up to the locks/raid. The changes depend quite a bit on the actual mechanics of any changes that occur, so speculation now I guess is a little silly, since the deltas on personal-gain versus raid loss are so close.

EDIT:
Your ninja edit made my point... damn you. Keep in mind the Shadow-lock v 2xSP ISB uptime becomes very dependent upon the amount of nukes the SPs are spitting out. That number can change quite a bit if I'm not mistaken. Regardless, the FIRST ISB-lock is very influential, so having one around is going to be a good idea assuming the "fake" patch notes remain fake.

Are all these Shadow vs. Fire calculations being made with the assumption that Emberstorm will give a 10% decrease to Incinerate cast time? Unless I'm mistaken it is still unconfirmed if it is indeed meant to be 10% and not 2%. I know its good to do all the calculations beforehand but can do you believe that they would make a buff as big as 10% decreased cast speed AND nerf raid utility by making ISB only effect the Warlock that proc's it? Honestly if both of these changes are true then all that is happening is that Shadow and Fire are swapping places and they will need to do something to Destruction Shadow to make it more competitive as every Destro lock will then be fire.

If your going to theorycraft about Fire vs. Shadow there should be number crunching of only a 2% decrease as well as 10% until it is known what Blizzard intends with that change.

I'm accounting for 10% casting speed increase on Incinerate but not accounting for the potential ISB nerf. 2% seems absurd. There's no rationale for the first rank of a talent doing something different than all other ranks, and I wouldn't even be considering 2% as something that could push Incinerate ahead of Shadowbolt.

The 2% is currently a display bug on the PTR, as several people have reported there's no decrease in casting time from having that single point in Emberstorm, and further ranks don't show the 2% haste at all from the first rank.

I ninja editted because the numbers were horribly wrong. After I figured out why ISB time was going up, I adjusted the ISB tab so it wasn't making Shadow Priests put up ISB. The correct number was about 50% ISB uptime on my own.

Shadowbolt does still scale ahead of Incinerate eventually, but I'm uncertain if something like 30% haste with 40% crit is obtainable or even optimal. It really looks like scaling is in Shadowbolt's favor still because of the increase of ISB and Bane vs. Emberstorm, but higher base damage on the Fire rotation is harder to overcome now.

There is no rational behind making fire a viable option. If they want fire to be viable, then the change to Emberstorm shouldn't be a decrease to Incinerates cast time but rather Transform: Mage. If they want different options in the end game raiding then they should work on having affliction scale with haste/crit gear.