I started playing around with the trial version of mudbox to see how it would run.
it seemed to work ok, obviously can't compare to a native windows install especially since the beta version of fusion is always in debug mode.
I only had 512 mb allocated to Windows but it seemed to run pretty good. However, I was getting minor graphical artifact/glitches when I was painting with the stencil tool.
Obviously I would not do any serious work on a virtual machine but it's kind of cool how there is something to look out for in the future.