Well I might be a great candidate for this question. Becasue I went from a high end video card to another high end video card.
I went from a EVGA GTX 285 F.T.W. to a Diamond 5870 some people even have asked why waist the money. Well I still think it was a better than great Idea.....
At first I didn't because I thought I didn't see that much increase from somewhat of my own doings with settings. And also because of premature drivers.....
But since I fixed some setting I over looked and then I downloaded the new 9.11 drivers. I'm in love with this card. Every game I have seen a substantial increase in Frames per second. It runs a hell of a lot cooler. It uses a hell of a lot less power. It overclocks like a son of bitch and still stays relatively cool.
And to top it all off...... with release of the 9.12 drivers that come out in December.... anyone who owns one is going to get a 25% to 40%(could be more) performance increase. Yes that high I didn't believe it either until I saw some of the benchmarks coming out with those new drivers.
The only thing I went down in is my Benchmarks. I chalk that up to the fact of loosing physx. But it wasn't my GPU score that went down it was my overall score. My GPU score actually went up. I also believe that once I add a higher speed RAM and raise the overclock even that problem will go away.
So if I had it to do over I would do it again. I great performance increase. As well as I got to come home to my comfort base which has always been ATI. But when the new drivers are released for this card it will get even better!