Myself and someone in my guild used wowhead to put together the ultimate crit geared FFB mage, and while i lost the link and am too lazy to do it again (you can do it for yourself on wowhead) we concluded that going PURE CRIT, gems enchants and everything, you could push 80% in a 25man raid. That being said, if you were actually going to do this, you would have to change your gems and enchants slightly to be viable.
After all the adjustments, we found you can have a mage in full 264 gear with approx 70% crit raid buffed and around 3k spell dmg unbuffed, you would also have approx 700 haste.
Keep in mind, with full 264 gear, an arcane mage is running around with between 1200 and 1400 haste, 3500 dmg, and 35% crit, all approximates, all unbuffed and depending on what trinkets you are using of course.
It would be interesting to see how these two specs played out, it depends on fight mechanics as always and skill. (rotations =/= skill, helping your raid while using every GCD does)
Edit: I was borred so i amde it again, heres Critmage:
http://www.wowhead.com/?profile=20674438