I can't comment on most of the higher end phones, but I'm in a pretty similar position, though, I'm more for music than gamming. I'm looking for open phones too though, I want hear what's around me. I've tried the the V6, 7506 (same thing) F1 and HD 590, as some top picks in my budget range. My favorite is the 590. I tried the F1 and the V6 side by side just the other day, and I liked the F1 better, but not by a lot. They sounded pretty similar actualy, the F1 were more open and a little bit more detailed, but not much, where the V6 had an even smaller sound stage but more bass. The F1 were indeed pretty comorftable, mostly beucase they were so light. However, I didn't find them nearly as comfy as everyone says, or as comfy as the 590. They would have been more comfy, exept that I had to push them down and forward somewhat awkwardly to get any sound stage out of them, and that caused them to sit strangely on my head and my ears sort of stuck out the back between the pads and the drvers.
Soundwise, I liked the 590 better too. It was comming off a bad source when I tried it, so I think that if I tried them both on a good source I would really like the 590 better. In my estimation, the 590 had better detail, much more open sound, more/better bass and a slightly less shrill high end, though the Sonys were by no means painful to me in that respect. In defence of the F1, even though it was on a full size CD player with a big and seemingly high quality reciever, and I liked the 590 better even on a sony discman, when I tried the 590 I had a music CD I had burned my self, so it was my own music that I was familiar with. Though, the F1 was playing Pink Floyd, Which I like quite well, but I didn't know the songs or the recording as well.
I'm not an expert, but I would immagine that the 590 would have more room to grow. Reprotedly, new cables such as the equinox make a big difference, and amp useage might be more key on the 590s since they have higher impeadance. (it's only 120 ohms, so it's not like portables and computers will havemuch trouble drving it, just not nearly to maximum goodness.) But again, I'm no expert, my opinions have been formed without knolege of what really good phones can do, and wihout trying phones in my own home. However, I know good sound when I hear it. I hope this helps, though I'm sure it will just add to the cnfusion, like posts here always seem to.