Well, if you go back you'll recall that I did post that the SR-009 and KGBH are better in several areas, but switching from that $8000 combo to a $4000 HE-6/ZDT combo doesn't make the HE-6 sound bad, just not as good (my ZDT has $ upgrades). While doubling the price doesn't give 2x better sound, it does give me better sound than any other headphone rig that I've tried/owned.
On the other hand, for half as much money I'd be perfectly satisfied with the HE-6 rig if I couldn't afford better. The contrast of switching from 009 to the HE-6 (or O2 Mk1/HE-60/HD800) after acclimating to the 009 isn't as dramatic as switching from SR-009 to something like HE-500, LCD-2 r1 or HD600. Switching down to the HF-2 is an even bigger "Yikes!"
Note - my the ZDT and EF6 are the best amps I have in terms of HD800 synergy since they're so picky, and with my other amps the HD800 would be ranked a bit lower and more on the level of the HE-500 or LCD-2 r1.
If I ranked my personal phones right now I might put it this way:
1. SR-009
2. HE-60
3. SR-007
4. HE-6
5. HD800
6. HE-500/LCD-2 r1/Lambda Nova Signature - tie
7. LA7000/HE-5 LE - tie
8. HD600/HE-300 r2 - almost a tie
9. HF-2
That can change tomorrow, and depends on source and amp. Any of those above except maybe the HF-2 could be someone's one and only phones, but my desert island phones would have to be the 009. Of the phones that I don't own, I might have put the K1000, Beyer T1, or PS-1000 at or near 6th or 7th... Also, my ES5 custom IEM sounds a little like a cross between the HE-6 and SR-009, which is quite good. So I'd be happy with those on a desert island too.