Other than a few codecs and hardware acceleration not working my VM's are perfectly smooth and play all games and applications I have tried. You must choose to only display on the ATI monitor and not the VMWare one if you want aero.
I have to say I have not had anything like the troubles some have. Once I found my working hardware I have installed and re installed dozens of times, windows just works no matter what order I do things. Install the OS, VMWare tools and CCC (although I am on an old version about 11.4) and it all just works. Windows 8 has behaved exactly the same on all my setups.
X58 is the king though, I have a UD3R board now with 4x PCIx16 slots and they all work for passthru. Currently have an Nvidia card for vSGA in slot 1 and 3 ATI cards for passthru. Going to give Crossfire a go just to see if it works!