Very good write up. That's a lot of amps being compared with 1 headphone. Looks like you did your homework.
When you said this headphone sounds really good out an ipod kinda is what I'm talking about. I could never say that about the HD800, LCD-3, HE-6, HD650, T1 and a few others. Yes, I'm aware these are open headphones, but my point is this is a headphone that's not as picky as some others.
The fact is, it's not hard to drive and it has a very low celling - meaning will not scale high at all IMO, so lower powered amps may be the best fit for it. However, you are correct the headphone needs quality amps to sound it's best. In my experience with this headphone, the amp really needs to take the bass by the balls and control it as best as possible. I've heard it sound muddy on some amps that wasn't up to this task. Also, the headphone is colored and forgiving when compared to other more neutral and revealing headphones, this is another reason why it will sound pretty good out of an ipod.
Anyway, very good comparisons.