#1 depends on your config you are running that card...mine are 100% stock CPU and VPU speeds......
I could easily overclock the cards, and get well over 20000.......
#2 that card is like what, $600???......I spend $379 each.....I'll take my 30% better performance gain for $170
Worst case, I can sell one of my cards, still have a great system, and put that towards something else....
#3 Nvidia Drivers are subpar at best right now.........My tests were running on Drivers from November......I'm sure newer drivers will result in much better numbers...
That said...
the ATI x850 XT is a bad ass card no doubt.....
But I've never liked ATI's drivers for games, they always seem to crap out and have problems...........