The first Hiper 580-R I got was DOA, so I had to RMA it. When you turned the PC on, everything would spin up / flash and then immediately power down - so when any current was drawn, it failed. The RMA came and I've been using it without problems since. The rails are very steady and are WELL within the error margins. It's virtually inaudible and one of the best PSUs I've used. I think that most manufacturers send out duffy ones every now and then, none are perfect ... but it does seem that Hiper do this slightly more than the better known makes (Tagan, Seasonic, Enermax).
Anyway, I think that the best PSUs about are probably Tagans. OcUK use these in most of their pre-built systems.