Yes, in fact we have been using Levitate, and actually it does seem like the only candidates for pulling "threat" on the Bone Warriors at the start are Onyxia's tank and healer, both of whom would have lost their levitate to damage. I can't wait to test this theory - thank you!!

Edit: March 7th - Finally got a chance to test this theory on Nefarian - seems to be that I can confirm Levitate was causing a problem. Hard to say... but I switched to only using Slow Fall and I had zero issues with threat.

A few more tidbits:

Omnitron: Ah, those stupid Mirror Images and their lack of pet bar. You should really make sure you cast them at the start of a new boss activating, while you're attacking that boss, lest they keep attacking the wrong boss and activate their shields. For instance, I discovered the hard way as I gave Arcanotron more stacks than we could effectively steal/purge.

Heroic Maloriak: Getting all the adds down during that Dark Phase before the first Red or Blue phase is paramount; perhaps even more important than the adds during the Green Phase. As a fire mage, that means getting the highest Combustion you can get with an Impact to spread it. I found I was getting the best results by getting a Hot Streak proc early but holding it as long as possible until the first adds spawned, followed by LB and Blast Wave. You stand a greater chance of being able to line up that Combustion with a decent Ignite + Pyroblast! + LB + Critical Mass and have an Impact ready to go. So fight that automatic urge to Pyroblast! as soon as the proc appears... and then save that Combustion for the next Dark Phase.

Valiona & Theralion:

Simple tip, but seeing as these share their HP, it's often worth it for mages (especially fire mages) to put DoTs on both targets. Plus, you can just keep DPSing the flying dragon without much of a problem: an added advantage of doing this is that the flying dragon tends to have the single target abilities, so you can more easily see when to move out of the way.

Al'Akir:

I assume this is common knowledge, but Ice Block dispels Acid Rain. Use wisely after a significant amount of stacks to help your healers out.

Seriously, don't do that on Valiona and Theralion. You can apply LB on both but keep dpsing the same as other people in raid or you would be missing important debuffs on your target.

Crit Debuff is applied by yourself only if you are a firemage, don't forget it and if you're the only one bringing it in the raid (10 man anyone ?), you're not giving it to other casters not dpsing the flying one. Your strategy works only if all casters remain on flying dragon. Pretty demanding, just to avoid potential munching for 15 secs every FO cd.

Keeping debuffs up is as easy as casting Scorch or Pyroblast every 30s--I don't believe there are any significant problems with this tactic.

Whether or not it's a valid tactic, dpsing one target or another is hardly a trick, nor is using ice block to clear debuffs. Let's try to steer this thread back towards the non-obvious.

For Nef 10 man (Normal, we’re not that good) I have had very good luck taking care of the adds as fire when partnering with a holy paladin running RF. He heals most of the initial incoming damage and after 2-3 get to him I blastwave/flamestrike to pull them off while FFBing the stragglers. After kiting over a frost trap I drop my ring of frost. When that is done I start the dragon’s breath, frost nova shuffle and they end up in a nice little pile. Our holy paladin comes along as a safety net for his stun, but so far the only time this tactic has failed was due to blatant mage error.

As Charlemagna mentioned, frost works great, and you can solo them in that spec. I just enjoy fire much more, particularly for phase 3 of that encounter.

If Valiona is positioned directly under Theralion in her ground phase, you can impact dots up to Theralion.

I did this several times last night during Heroic V&T attempts, here's one log from it:
World of Logs - Real Time Raid Analysis

log snip-
[17:23:45.812] Valiona afflicted by Combustion from Penjeh
[17:23:46.377] Penjeh casts Fire Blast on Valiona
[17:23:46.661] Theralion afflicted by Combustion from Penjeh

I only impacted successfully when the tank had Valiona posititioned under Theralion about where the back of her neck was right under him. Slightly off center with her butt-end further from the center than her head.

Maloriak Heroic: If you own DMC: Volcano, equip it right before the pull. This will trigger the internal cooldown and the card will procc right at the beginning of the dark phase, giving you higher ignites and combustion to spread.

(this was mentioned in the Simple Question/Simple Answer thread, but imo deserves a more prominent post here)

I will confirm this on our next Maloriakkill this ID, but my reasoning last week was this: By equipping it just before the pull, the card proccs early enough to build a big ignite&combustion on Maloriak himself, which can be spreaded as soon as the adds spawn. If you leave it equipped, the card will procc too late, at least in our raid, where the adds are pulled away from the boss quickly.
I could not find the timer for the first dark phase, but I will measure it on our next attempt.
I prefer building the combustion on Maloriak instead of an add, and damage on Maloriak himself was no problem anyway in our raid (we even had to stop damage for another green phase to occur).