6970 CF scales excellently and doesn't have very bad stuttering issues. Drivers are usually fine, but they are a more valid compaint than the other two with the 6970.
Thanks for that, friends have personally had horrible experiences with 6900 series CF, so I steered away from that. I'm well aware of the 6800 series, however.
Also about your recommendation of an HD7950, I would agree considering AMD has yet again dropped the prices (forgot about that ) If you overclock, I'm pretty sure it'll kick the heck out of the 660 Ti.