With the crit nerf in Cata, HS procs are less frequent. I have begun pre-casting Pyroblast as the tank is about to pull for boss fights. That gives me Critical Mass, Pyroblast DOT from the start. Next I do a Living Bomb and by that time the GCD is ready, Pyroblast's DOT started its first tick and Ignite starts rolling. From here I pop Combustion, Mirror Images and start my FB nuke to 40%, evocate, etc.

I haven't experienced any threat issues because I am conservative and by the time the tank pulls, I have 2 seconds left on my cast. I am not trying to time my cast so I hit the same time as the tank pulls. But I see this method as if I am casting a Fire Ball, because I have already casted ~1-1.5 seconds off my Pyro. I also run with my guild which includes competent, aggressive tanks.

This method could also work well for multiple target pulls where AOE is appropriate and you want to DOT up a single target, Combustion, Blast Wave, Impact.

Has this been considered before to get your Combustion rolling asap?

It's modelling a single target rotation, where Fire Blast isn't used at all. For any fight with dot-spreading or AOE potential, Impact is very strong, but can be incredible when used in conjunction with Combustion.

You might be thinking, "But AOE / Multitarget is situational". True from one point of view. But pure single-target DPS encounters are situational now as well from another. It really depends on what you want to optimise the spec for, and whether you're prepared to respec between variants for a very minimal potential DPS gain. A gain well within the (large) variance Fire currently has.

Players have thought about having a mainspec "Single target Fire Spec" and an offspec "AOE Fire Spec". It's certainly something one can do, but many players will just recommend to have a Fire spec and a Frost OS for control when needed, given that the difference between the two Fire specs is almost trivial. Again, it comes back to player choices.

The value of Arcane Concentration was concluded to indeed be a single target DPS gain, but a very minor one at that. Around or less than 1%. Furthermore, the first point maje concluded was the most valuable - with the second and third being worth an even smaller fraction of that.

Off the top of my head, here are examples of several fights which either have AOE or Multidot potential to various degrees where Impact sees strong use, stronger than the ~1% AC could offer: Halfus, Magmaw, Omnitron Council, Maloriak, Conclave (Depending how you handle adds),

I'll also note that readers might be thinking, "Drop Cauterize!". My experience with this weeks worth of Cataclysm raiding reminded me why I (personally) consider this an essential talent. There are multiple fights where this talent can save you from frequent mechanics which can easily kill you, even if you personally are playing well. Other players will be responsible for key interrupts, for topping you up before incoming heavy damage etc - and it'd be foolish to think everyone else will always do their job perfectly too. Maybe someday during farm status we'll think differently, but certainly not now - and especially not during Heroics soon.

So my point is:

From DPS (not surival) side: Runspeed was always superior to other enchants, when we take in account, we are not doing DPS (in sense minimal amount of DPS) when we are in move and taking new position. In case of fire mage, we are doing 90% od damage (scorch rotation) of static rotation (fireball rotation) when running. I suppose this enchant need deeper analisys (how much time u must be on the move to make mastery-runspeed enchant superior to hit enchant.) (if I'm right, the better equipment u have, the hit enchantment will be worse) For more, we can just use this time as mana efficent time. (I'm not smart enough to take up the challenge to calculate this on numbers)

And from survival side, whe always have blink, and now some other tools to get out from sticky situation (for example molten shield).

I can't put a statement that 50 hit enchant is always better, but it should be reasonable alternative for most fights.

edit: Tyrians point about void zones and buff is valid. Disregard this post.

Every spec should have Impact unless you are specifically fighting a single target boss and have a custom made spec for that boss only. Impact's value is worth it even if you occasionally have a second target and want to spread dots to it. Then on fights such as Maloriak or Halfus, a single Impact'ed fully charged Combustion can do 15-20% of my total damage for the entire fight, let alone the Ignite/Pyro that was also spread via Impact.

While you are trying to sound nice, you are still selling Fire-Scorch as completly unviable.
I think it would be good to add a few more facts:

In T11 ilevel 372 gear Fire-Fireball provides ~10% more DPS than Fire-Scorch for Patchwork Fights.

~3% of this is T11_4piece
~3% of this is Glyph of Fireball (vs. Glyph of Living Bomb)
Fights with (unexpected) movement or knockbacks will reduce the DPS difference.
Fights with adds will reduce the DPS difference.

While it wasn't intended to sound like that, I agree readers might draw that conclusion. Thanks for the feedback. With this in mind, that section in the OP was rewritten to sound a little less like Scorch Rotations are a dirty (or even wrong) thing to do when the situation calls for it. For easier reading, casting only Scorch in rotation is being referred to as a "Pure Scorch Rotation".

As far as I've been able to tell, only the character sheet crit rate affects the chance of T3HS. This would seem to imply that the FB Glyph would not decrease the T3 HS per-crit chance, but I've not tested it, partly because testing it will be difficult due to the enormous number of casts required to test it correctly.

Assuming that the FB Glyph does not affect the T3 Per-crit chance, it would increase the value of both T3 and T4 HS, relative to the FFB rotation.

A few PM's from readers saying the "Use Scorch Rotation" section still wasn't written clearly enough. It was thus rewritten again for better clarity. We're trying to explain that both types of rotations (Pure Scorch and Burn Rotation) have a time and place. Players shouldn't feel dirty for "Resorting to using Scorch", but should embrace the rotation when the time calls for it. And also to be mindful that there are times where the Burn Rotation is strictly superior and preferable, too.

I'll try to convert all this into something more tangible (and practical) players can relate to.

Here's a log for my kill of Atramedes (10) earlier tonight: World of Logs - Real Time Raid Analysis

The relevant information to look at is not my dps, but spell damage sources: Scorch and Fireball. Atramedes is a textbook example of a fight where players need to embrace Scorch - and shake off the idea that "I should always cast Fireball where possible". This is why the appropriate sections of the OP are being rewritten, to make this clearer.

There are some periods in the Atramedes fight (Air phases) where you are moving nonstop for an extended period, and stopping to ever cast Fireball is often not possible, nor worth the risk. Other sections of the fight you may squeeze in Fireballs occasionally, but again, the large amount of movement required (Discs, Sonic Breath) will often quickly force you into Pure Scorch Rotations.

For this fight, i'd recommend players initially treat it as a Scorch fight. Once you become intimately familiar with mechanics, and won't fail them due to trying to cast Fireballs more frequently (aka standing still more often), start shifting into Burn Rotations where possible. But if you try to do this in reverse, chances are you'll be failing sound mechanics more often - which is a much bigger problem in the grand scheme of things. As you could tell via the Scorch damage in my log, I simply wasn't able to burn enough mana due to the constant movement required and number of Scorches therefore cast. Ending the fight at 0 mana just wasn't really possible - and I even used Evocation either - despite this being a 8.5 minute fight. These are all things we know we should aim to do, but sometimes it just isn't possible due to the unique needs of each encounter. In hindsight, I probably Scorched too much and should try to squeeze more Fireballs in, instead of playing it safe by constantly moving. But, being the first raid on Live with him, we wanted to play it safe in general.

You can see Elluminae doing this fight as Fire also here: World of Logs - Real Time Raid Analysis

Notice that Fireball was the main contributor for him/her. The difference in results comes down to various factors such as: strat, positioning (very important), skill, natural spec DPS variance, raidcomp, practise and experience with the fight, familiarity with the spec in general - and so on.

This particular fight also solidifes why Fire is king when it comes to choosing a Mage spec which favours Mobility.

Edit - I could go on writing about the various problems of Fire being exposed in current raid fights. High DPS variance, dependancy on Crit, Combustion being frustrating and awkward to use. But i'll skip those (for now) and keep this post strictly about Scorch, until more people are doing said fights and can relate first hand. All these points were documented well before release, during beta, and can be found in threads such as this one: Fire Mage: Lvl 80 vs Lvl 85 Comparison - Forums - World of Warcraft

Edit 2 - To the below poster, that's true. I rewrote that line to be:

This is a minor point, but the original posts says:

"Your goal is to end each fight with exactly zero mana. Unused mana is wasted DPS - you should have started casting Fireball earlier to burn it off."

To the point you just made, this is not entirely correct. On heavy movement fights when casting free scorches, you may indeed end up with mana remaining yet have put out the max dps given the mechanics.

I tried Argaloth again this reset, and found it pretty easy to follow the "Ideal" mana plan outlined several posts back, and in the OP section. This is pretty good starting practise for raids. Just need to be mindful that Argaloth is certainly not the norm for encounters, and players will ultimately need to learn to deviate (to varying degrees) in pretty much every other encounter.

Just takes some practise with a couple attempts to gauge how long 35%->0% will actually last, which in turn will determine what size Mana Reserve you'll need to have on standby immediately prior to Molten Fury range. (Controlled via Hover Rotation + Scorch Weaving).