Like I said, it's ultimately a matter of how one justifies it. We can debate to eternity and still would not be able to come up with a definitive conclusion that we could both agree on as there are a variety of factors that are difficult if not impossible to accurately and consistently quantify. In other words, it is a very relative and subjective topic. At least, I attempted to have some sort of controlled comparison by isolating complicating factors to the best of my ability/knowledge and providing numbers/computation. That's all we can do in this matter. If you're happy with the justification of your PSU choice and I'm happy with mine, that should be good enough.
Detailed PSU 80 Plus certification results here:
http://www.plugloadsolutions.com/80PlusPowerSupplies.aspx#
I'm not at all disagreeing with your method, just that your numbers don't match with my experience in terms of the average price difference. It's not a matter of justifying my choices at all, I don't actually use ATX PSUs at all for mining, other than for some testing. I don't need the minor rails so I generally just buy server PSUs. It's hard to beat the value of a 2450W Platinum PSU for $50. Detailed PSU 80 Plus certification results here:
http://www.plugloadsolutions.com/80PlusPowerSupplies.aspx#
Is there an interface board available for the 2450W PSU? I have a Delta DPS-2000BB with a Gekko Science breakout board, but I like the idea of a Platinum PSU. If there isn't a interface board available, would you mind sharing how you wired yours?