You should check your facts. It looks like you refer to the 80 Plus certificate, but misunderstood it. It doesn't mean most efficiency at/above 80% usage, but 80% efficency in general, leading to 20% energy lost to heat. Every PSU performs best at 50% load. Check the table at wikipedia:
http://en.wikipedia.org/wiki/80_Plus
this person is totally correct in what he is saying. I had a nice power supply, forgot to add up power usage and it ran at 85%. it lasted 2 months and went to the power supply heaven with a big bang. The bigger it is the better