Magick Man (and others) --
I agree with your point on multiple rigs -- for sure no one is saying you only need one. I didn't mean to imply that! I only wanted to say we all should "stop upgrading" at some point. Be happy with what you have, enjoy music and the people here, don't keep buying gear constantly.
I have certain CDs that "demand" certain phones -- that's why I keep them in addition to the Stax. And collecting is different, that's why for years I hunted and fnally bagged an Orpheus (but not at today's insane prices), and would love to add an R10 ... but I am not thinking I will have better sound. Let me re-phrase my point this way: There's listening to music, there's collecting vintage headphones for the same reason anyone collects anything vintage, and there's constantly upgrading. All three are different activities. Thumbs up on the first two, thumbs down on the third, and a suggestion to spend money on music and Head Fi friends instead.
And since this is turning in to an 007 vs 009 thread, let me add my opinion: I own O2 Mk1 and O2 Mk2 (Spritzer mod by Spritzer himself). Both of these, with KGSS or 717, are slightly inferior on both orchestral works and (mostly female pop or jazz) vocalists to the Orpheus. With Kerry's BHSE, both are superior, but each has a slight problem with smoothness of frequency response. The 009's I have only heard at meets, with (a different unit but same tube complement) Kerry BHSE, and it seemed perfect. IMHO only.
For rock, especially live concert albums, and for hard bop, uptempo pop and country, etc. I use dynamics, typically K1K but sometimes AD2K, HD800, beyer T1 or Denon D7K depending on the recording and whether or not I am alone in the room. I will sell them all except the K1K at some point. (Well I need a closed set so I'll keep the Denons until I score an R10). I have them only because I kept "upgrading", which brings us back to the point of this thread. I had HD600's, but "had" to get 800's. I had beyer 880/600's but "had" to get T1's. I had Denon D2000 but "had" to get the 7000's. Stupid stupid stupid.