^^Yes. That's true. Although its a reputed brand, their PSU's are not that up to the mark. Corsair should be the default choice. There is one Seasonic 650W 80+ Gold certified one as well. You can look out for that.
I have two OCZ drives at work, a 400 watt SteathXtreme (running a C2D 5400 @ 3.5Ghz and a Radeon 4650) and it has been solid as a rock and pretty damn quiet. I also have a 700 watt ModXtreme one, running a i5 750 @ 3.6Ghz (w/out turbo) and a Radeon 5770. It has also been as solid as a rock. I have a Corsair HX850 at home, running loads of stuff, and it ALSO has been as solid as a rock (not surprisingly, as Corsair are supposed to supply the higher quality parts).
So I would say this:- If you want to save money, get the OCZ. If you want a spoogeworthy PSU which will outlive cockroaches in the event of a nuclear holocaust, then get the Corsair. Cant comment on the XFX ones.
But honestly, the new StealthXtreme 2 PSU's are good quality, I would say. More efficient than the previous gen too, from what I gather. So dont be scared of saving a few quid and getting one