i will just say this. i have raided as both frost and fire. as frost, prince kept wiping my group (the boss a top kara). as fire, i was able to burn him down MUCH quicker. also realize, there is a fire talent that increases dmg done to targets under 20% health by 10% (it could be other way around, i dont feel like lookin it up right now). how is this significant? most bosses will have around 100k-1000k left at 20%. that means that ur dmg against them will be increased for a VERY long period of time. plus the DoTs from fire crits further extend the dmg done and cast time on a raid boss isnt the beat all end all stat.

i donno. in PvP/arena, frost mages tend to do more dmg(personal experience, not written in stone) due to resilience nerfing the big crits from fire. soooooo, imo, both have significant DPS output, just know which one is more geared for what ur doin