Yes well you can get bad performace with gforces too, but in gneral everytime ive ever used maya on a computer with a ATI all-in-wonder 9800 pro it was like mashing my head against the wall, sometimes it was missing manipulators and sometives missing points etc.
BUT yes you CAN get bad peroformance out of a gamer GFORCE... the deal is that with gforces the difference betweena stable driver and game optimized one is huge. Also must admit it that theres many other reasons maya might be slow than just the graphics card drivers.
And yes some gamer geforces work better then others.
Nevertheless i wouldnt consider a ATI for maya use. While i personaly would RATHER use a ati or 3dlabs for philospophical rasons, its just not worth it because nvida is so much better.
But the point is that most glich quetions on the forums are from ATI users. Anyway i personaly usa a quaddro just because theres a guarantee for no glitches.