Not sure if someone found solution to the problems, but this is how I understand it:
ATI = Native resolution, full QE/CI, graphics glitches
NVidia = Boots only to safemode, without QE/CI, some has got it booting without -x, but still no QE/CI, no information about glitches
So I think ATI is kinda "the winner" atm, but it still has some glitches.
Like I said, try disabling the power management in the ROM, you can find instructions somewhere on the AMD Development section.
For Nvidia Fermi (Maybe Kepler) disable GeforceGA.plugin and GLDriver.bundle in System/Library/Extensions. This will allow you to boot without -x (safe mode), however no acceleration. My 9500GT works just fine, the GTX560 is the b*tch.
For anyone with bootdisk / Installer issues:
I would try to just download a clean VMWare image. I downloaded 10.8.2 and mounted it to desktop. I then cloned that drive to my partition using disk utility. It makes it easier and faster. Then you can do some real troubleshooting. I am going to worry about a boot disk later. I have my snow leopard boot partitions.
Here are the VMware mounting things. Put them in Library folder in the same labeled folders. If it does not work then google for VMWare image mounting os x.