There is a person selling a ATI5850 Black edition for 300 Bucks Canadian.
Now i need to know how much real FPS Gain i can expect to see with the ATI GPU VS my GTX260(196 Core). Keep in mind that my GTX260 Overclocks pretty good on air, 702 Mhz Core
1404 Mhz Shaders
1240 Mhz Mem clock (2480 Effective)
I am only bringing up my Overclock because I do not want the ATI 5850 compared to stock GTX260 Results.
And according to this page (With my GPU Overclocked to close to the same speeds), I am close to the GTX285 in Crysis 285
Gigabyte GTX 260 (216SP) 896MB Super Overclock Review
But I am unsure how well the ATI5850 stacks up to GTX285
I do not want this to turn into anything other than pure performance post.
Who is faster in most games, And by how much

Lets keep it clean guys. I just have a chance to pick this Bad boy up for a good deal. Just would like to know besides the DX11 stuff, Is the ATI worth it. Yes there is the whole DX11 issue. But i am just concerned with Raw FPS guys.
Cheers.