I dont think that would happen, the first time naruto went kyuubi, he went berserk, and attacked haku in a mad rage ( his power was obviously more feral then the other times he used the kyuubi after that, even running on hands and feet).
Kyuubi is supposed to be a NINE-tailed beast, while when naruto fought sasuke he developed only 1 tail, this to me means naruto was only using a 9th of kyuubi's power.

Now this leads me to believe that kyuubi was tricking naruto, there is no way in hell that naruto's mind and body would be able to handle 100 % of kyuubi's power, especially since it's a dark and sinister power.
And naruto's body was already "breaking up" at the climax of that fight.
I can just picture naruto breaking the seal and blowing up afterwards or something..... kyuubi would definitly take over.