To help get us get back on topic, I'll share a little anecdote. I recently visited a professional mastering engineer who works with a major symphony orchestra, with millions in the budget, and when I went into his studio to see some of his gear, I was happy to see a pair of HD 600 on his mastering desk. There were no other headphones around, except a few DT 770's in the recording room, for the musicians. I knew he could afford HD 800 and even more expensive headphones, so I asked him why he only used the 600. He said it was pure ignorance to believe sound stage is anything special... It simply is the way the drivers are positioned, and that affect is not always desirable, especially since it always creates sibilance issues and pushes the music farther from your ears. The point of using a headphone in addition to monitors is to bring the music closer to you, so you could work with it intimately. He basically thought the HD 600 was a better headphone that the HD 800, and didn't pay any attention to the price differences. He said he uses it a lot during mixing and mastering and sometimes even forgets what's playing - his monitors or the headphones. He said the 600's are natural sounding headphones and people shouldn't be afraid to mix/master almost entirely on them, and, according to him, they'd only really need monitors when checking for reverb, since headphones don't interact with the room.
He wasn't a headphone nut like most of us here, so he quickly changed the conversation and talked about other things even more enthusiastically (his mixing technique, how he deals with musicians during the recording process, how he takes detailed notes of everything happening in a notebook during takes, etc.). But I kept thinking about his HD 600 comments all evening.
He is a wise man.