i'm running Maya 2011 on a 12-core 2.93 with 24GB RAM and ATI 5870.
i've been experiencing problems with some very annoying viewport lag. when i have all 4 viewports shaded with a smoothness of "2" or "3", and i'm in one view, and i try to exit that view with "spacebar", my screen turns dark grey and i get the spinning beach ball for like 5-12 seconds until the four viewports show up. i've called Autodesk, and we are trying to pinpoint the problem. when they tested my scene on their iMac with an ATI 4670, they experience no viewport lag at all...such a pain.
another problem is Mental Ray Satellite rendering. with four extra computers, 8 extra Intel processors and 16GB RAM, rendering along with my 12-core Mac Pro (master), my renders don't go any faster. they render in the exact same time, sometimes a second or two faster. i was told by Autodesk that Mental Ray Satellite wasn't really designed for small render farms, but for major setups. i'm not sure, but i think if i buy a Mental Ray network license, and install on all my satellites, that this might make a difference?
i'm also very curious about this new Quadro 4000 for Mac, and how it will enhance the Maya 2011 experience. i wish Autodesk would test it out with Maya 2011 before the graphics card ships. i'm not shelling out $1199 until i know it'll perform well beyond the ATI 5870.
all in all, i've seen plenty of bugs with Maya 2011 for OSX. but what bothers me the most is the lack of proper customer support, technical support, hardware/software qualification, and the fact that Maya can't utilize a GPU to properly optimize the viewports (ie crossfire, CUDA realtime rendering, etc).
i'm definitely losing my patience with Autodesk. I don't think I'll be shelling out any more money to Autodesk until they get it together.