Got an older pair of Alphas, and I must say the hype is real. The details are fantastic, and the mids and bass are life-like. I don't think mine has the treats, and yes, the highs could be piercing at some point, or even sibilant, but I believe the treats will treat them (will order them soon).
The finishing on these headphones are really top notch. They are just beautiful headphones, and precisely manufactured. The comfort is fantastic, and it is very easy to fit them on my head with a great seal.
My wife commented on how good these headphones looked, and when I gave it to her for a listen, she went through three songs before she gave it back to me (she normally listens to one song and that was it). She's a classically trained pianist, and plays many other instruments as well, so she has way better ears than mine. Her first comment was that they sound very detail, and that the songs sounds "higher pitch" than normal (she means bright), so it pretty much goes in hand with every body else's opinion.
One note of caution though, I was driving them out of an iMod with a quickstep, so it's not the best set up.
Compared to my Koss ESP-950 with Stax SRM1/MkII set up, the alpha dogs seems to be even more details, but the sound isn't as warm and musical as the Koss. The bass of the Alphas hits a little harder, but the Koss just has more presence. The mids on both are equally great, and the Koss seems to have more natural highs. Sound stage goes to the Koss.
I think I need a better setup for these alphas, and can hopefully try out a bunch of amps when a head-fi meet comes along.