When I first started doing heroics and Naxx at 80, I was Frost, and it did well for a while, but once you get to a certain level of gear, you'll notice that your average boss-fight dps won't be going up too much. It'll feel like a brick wall somewhere around full heroic/Naxx10 gear, which I finally climbed over by going to a FFB build. This pushed my dps much higher, but I just recently hit another snag in Ulduar, and had to go to an arcane build. The FFB build is comparable, but slightly less dps for me. Personally, I think this is due to the high-mobility Ulduar fights require, compared to the stand-and-nuke ones in Naxx. FFB has such a long cast time, it's difficult to push as much dps as you can in Arcane. /opinion

Anyhow, what I'm trying to say is while it's nice you can push 3k under full procs/cooldowns, what's your average dps over say a 5 minute duration? Anything close to that? If you've got yourself about 1600+sp and 20%+untalented spcrit or so, you might want to give FFB a try. You could be pleasantly surprised.

I do love frost, and wish it were raid-viable. When raid's over, I swap back to my frost dual-spec to go have fun.