Hey, this is just a thought I came up with while comparing DPS of different speccs to each other. The first thing I noticed was actually, that the 40/21/0 specc, that is often thought of as crappy, due to the worse SD-scaling, actually scales darned well with critchance and mana, which both are pretty decent in raid-buffed situations.
Next thing was, that in boss-encounters everything starting at pyro to blastwave isn't actually soo good for raiding, in terms of DPS-increase. So why not give up 1 point in Mind Mastery (like 35SD @ 700 int) and get elemental precision, icy veins and pyroblast? Given a decent critchance and loads of intellect that could actually bring you pretty close to the DPS of 0/50/11 or similar speccs, while not having those brust-damage issues of deep fire on trash pulls and insane DPS with arcane blast spam on short fights.
Of course you actually lose quite some talents in fire, that are useful, but since ppl report, to have too much mana left that couldn't be converted to DMG during the fight, I think Master of Elements isn't an issue, as well as improved scorch, if you're going with other firemages. Burning soul is also handy, but seeing how frostmages can live without it, I do not see why its so important.
I'm not anywhere near good geared for raiding, so I actually didn't run any kind of test, also because I couldn't compare deep fire really well, since that only shines in raid-buffed situations and with a lot of SD, and I don't have too many of those situations, seeing how I'm no raider :p
Icy veins could help sqeezing in about 6 fireballs and instant pyro, while without you'd only be able to do 4 fireball and pyro during AP-phase normally, maybe even better with haste-rating, and haste-procc.