Interesting thread, figured I'd weigh in as I have some fairly recent experience with the SA5000. I tried them out earlier this year (month or so ago, now). I found my K701 to be better than the SA5000 in every way possible, and the MDR-F1 to be the headphone I was hoping the SA5000 to be (a good complement to the K701; it's better in some regards, worse in others - it stayed, the SA5000 did not). The talk of dampening in the SA5000 housing has me thinking of the F1's "Acoustic Bass Lens" (and despite half of the English section of the manual being devoted to this feature and why it makes the F1 the best thing since sliced bread, they hardly describe it any meaningful way, the pictures make it look like a big piece of unobtanium between the driver and the protective grille though - sort of like what the markl mod did for Denon drivers).
I'm curious in reading more about the "fake SA5000s."