Who said you can't overclock at all? It's only because CCC doesn't allow higher OC's than 790MHz. It will, and has already been smashed.

And about the "problems" 4000's have; a lot of people here bought 4850's and 4870's; and only a few guys bought GTX 280's, guess why; because of its price and its, to me, lackluster performance.

So it's normal that there are problems being reported for 4000's, but not for GTX 280's.

And SLI is as much problematic as CF, don't worry. As long as both use the f'king AFR mode (without delays) they're all going to have microstutter, and they're all going to suck whatever you do.