The extra few percent is nice, but you want to avoid being "penny wise and pound foolish," i.e. you may not recover an additional $50-$75 spent on Gold over Bronze, especially if the PSU is not often operated in an efficient part of its range. Regardless of which 80+ level you choose, overall quality still needs to be your #1 criterion. For example, I'd take an 80+ bronze from Seasonic any day over an 80+ gold from Sirfa; the former's internals will be better. Seasonic, Delta, Super Flower, and Flextronics are the OEMs I'd consider. FSP isn't bad, but when the other four are available (assuming they are), I'd probably pass on them too.