I bought a GTX570 and after a few concerns it's abosolutley fine bar one of the DVI slots not working, which aint the end of the world for me, however some could see this as an issue but the saving in the region of £100, not with me.
Although was slightly annoyed that the cooler was different but OcUK weren't to know until they received stock, although I read that Gibbo posted they could be refunded but to save hassle I've just removed my soundcard as it restricted airflow.... (Shouldn't of bought a micro board)
I'm just glad I didn't get MooSey-UK's.....

but maybe that would have worked in my setup, who knows.
If you do decide to buy one, ask about to see if other people have similar setups to you to determine how they perform, MooSey-UK and Jinjur both have Q6600 LG775 setups and both had problems with their GTX570's where my Phenom 955 AM2+ setup is now rocking!, anyway just a theory.