I used another PSU calculator than you did and also "upped" some of the parts he had installed since it is bad to run a PSU on more than 80% load as far as I heard.
I'd agree with you for only one reason, the reason being that if he bought a bad PSU. I have a Antec VP 550, it guarantees that it will give you EXACTLY 550 Watt, nothing less, nothing more. So it's enjoy for my PC.