GambLBoth are pretty darn rare as far as consumer level, you might get lucky and someone heard them at a show but this question probably won't be answered for about 6 months :)
GambLThe original mahogany TH-X00 was really similar to the TH-610, in fact I didn't really find much between them. Had a chance to compare both at length, and ultimately sold my X00 to move up to the TH-900.
A pic I took while comparing both, though can't really tell you if the Ebony or Purple Heart sound much different.
GambLWell, if you're only going for one, I'd say you'd be happy with either, even the mahogany was a solid, fun headphone. But if you already own one, personally I'd say don't bother. Even at $849 minimum for two variants, you're getting close to a new TH-900, and could probably find a used one for very little extra.
Personally, go for whatever you think looks best, I'd say.
Lyer24It seems to be less sparkly to me after some use, I wonder does it need proper burn in. I know Metal571 had had the Eikon for a month and said the sound changed over time and that was also a biodynamic driver.
I am actually enjoying the highs more, it's like it has settled and bass is better. Thanks for overview.
rslataraHaha, in my limited experience, biocellulose drivers do need a bit of break in, though the 11kHz spike on my X00EBs still sting a bit. I don't listen to them as much nowadays though, since I got Klipsch HP-3s for an excellent price and it's basically a marked improvement over the Fostexes, though there are maybe a couple things that the Fostexes do better than the Klipsch.
The Fostexes really like tube amps, or hybrids with low-z. Might be worthwhile to invest in one!
Lyer24Yea I have an xDuoo TA-01 and TA-10 tubes sound amazing on the TH-610. It was harsh to my ears but now it just sounds great. That Klipsch HP-3 looks pretty darn nice. Actually can't take the Fostex off my head.
I am also using these pads which I have a few spare sets of, the ones in the middle. They are like a beefy lambskin version of the stock design and combine with the the Dekoni ring it beats every other pad I have tried including Eikon and original TH900 pads. ;)