Hi, I think electrical noise is partly luck of the draw. In general having better quality PSU will reduce the chance, but not eliminate the possibility it will do it under certain circumstances.
I would suggest your chances of electronic whine are similar between any high end Seasonic PSU
Unless you're going to be using *A LOT* of watts through your PC all the time the difference in efficiency isn't going to be significant on your electric bill. Nor will it affect noise levels, by time pulling enough watts to make a difference to PSU cooling everything else will be rather louder!
Enermax do a 500w Platinum PSU and 600w (and higher) versions with bigger selection of connectors, it would run almost any PC.
[My [email protected]
+ GTX560 Ti can be run from S12-II 330w PSU!]