CCF, thanks for this awesome post as I am having similar issues and have contacted NVIDIA. A very helpful support tech has passed this onto the team and they are looking into it.
The thing is - ProTools video performance is so much better now as far as I can tell, and also in Nuendo it looks smoother (I had had to disable AERO before to get playback without micro stuttering, but that resulted in tearing due to disabled v-sync) and better but Nuendo hangs every now and then.