Hello, I'm sort of new here (been lurking for a while though), and I tried out the new beta driver on my EVGA 7800 GTX 512. I was previously using 84.43, and I ran FEAR's benchmark program once for 84.43 and another one after installing 91.28.
The results were 24 min, 43 average, 73 max with 84.43, compared to 27 min, 46 average, and 80 max with 91.28. It could have been a minor random fluctuation since I've ran the tests only once each, but I think it's rather safe to say that there is an improvement.