As many have already posted, we all hear differently. Physical measurements of headphones are fun and might give you some pre-purchase guidance, but actually hearing/auditioning for some time with your own music (if you are buying headphones for yourself) is obviously better, especially if you can do this in your own comfortable setting.
Since so many retailers have excellent return policies, and since there is a strong used market, this is a viable strategy. Yes, auditioning will cost you money (shipping, or the loss on the buy-then-FS transaction), but you should correctly count that as part of the price paid for the HPs you keep.
I am a well-regarded statistician and understand the scientific method as well as anyone, so let's not go there in response.
I own beyer 880/600s (MANUFAKTUR from the German site). I purchased a QESLabs HPBA balanced heaphone amp speficially designed for these phones -- it is solid state -- and had the 880/600 re-cabled for balanced operation by Headphile.
I own beyer 880/250s. These came with a single-ended SS amp directly from beyer specifically designed for these phones. (The amp also has DSP functions, but I turned those off).
My Wadia CDP has both balanced and s.e. analog output from SACDs active, so I am able to drive both amps simultaneously, and level match with no problem.
With some long audio cables from BlueJeans, I am able to sit comfortably in a desk chair and have access to both phones -- level matched, as I said.
I put on an SACD that I know well, and close my eyes. My wife switches the headphones for me when I tell her too. The clamping force is identical (no, I haven't measured the newtons, but I can't feel a difference). The pads are identical. I repeat with other SACDs. Clapton, Joplin (Janis, not Scott), The Who (Tommy).
I (strongly) prefer the 600 ohm setup. My blind A/B score was 25 out of 27. (If I was paying attention, instead of enjoying the tactile experience of the wife/hair combo thing, and extrapolating where that vector would lead, eyes closed really amplifying that too, the score would have been 27/27).
Could be the amp, who knows. But each amp was designed for the HP it was driving, so I am testing the whole package. The amps cost about the same, and one was made by beyer itself.
When I return to my normal wiring set-up, the 880/600s are right at hand, as is my Orpheus. Both are on all the time when music is playing (the Orpehus is s.e.). On anything pop (except solo femal vocalists) and rock, I tend to pick up the 880s -- that says a lot. For symphonies, classical violin and piano, female torch and slit-your-wrist genres, and opera, it's the Orph for sure. For classic album rock, rap, and dance pop -- as well as the re-mastered Paul Simon collection and the Beatles mono box -- it's the 880s (for most large live rock concerts, a genre I like a lot, if I can motivate myself to get off the sofa and cross the room, I still prefer the Beta 22 and the AD2K's).
So for me, IMHO, the 880/600s deserve all the praise they get. There is no BS here and the thread title is a tad offensive. The 880/600s are an important product in this space, and the MANUFAKTUR site is neat and adds to the pleasure of purchase. I usually recommend this route to new audiophiles just getting in to HPs. (First I recommend used Stax, but that doesn't often curry favor ... however eveyone loves the MANUFAKTUR experience).
880/600 BS? Yea, Better Sound.
Some of the posters here live near me and come for listening sessions -- I think I will try to repeat this single-blind experiment. But they have to supply their own headphone-changing-girls, sorry.