Jochen, I have both the T100 and T200 and (of course, since I bought them) find them to be an exceptional value as players. The T200, new in box, for $1,400 would be an absolute steal IMO, so much so that I'd be tempted to buy a second one for another system I'm putting together.
I can confirm that the T100 does decode HDCD but the T200 does not. Why, I'm not sure, but that's just the way it is.
The headphone out on these players is what you're most interested in and I can tell you that you would be in for a real shock! The great thing is that you can tube roll it just like any other tube based headphone amp, and with a pair of NOS Northern Electric 396A tubes, it really comes to life! There was a time when I thought about selling off all of my headphone amps and just use these players for my head amp needs. But maybe this was just the initial shock that the headphone outs sounded so nice and smooth. In truth, I've only briefly compared the head out (i.e., direct to headphones) to the tube out going to different headamps to headphones. But from my brief listening sessions, I found the direct head out to be on par with the likes of the RKV, Sugden Headmaster, and micro ZOTL. These were my immediate impressions and I didn't do any serious comparisons, plus a lot of time has passed by since I tried this. I could spend some more time with it if you would like (it would kind of be fun actually). Any particular headamp "flavor" that you're interested in? I've still got the above amps, plus the Stealth and Maestro ZR (I'm thinking tube amps would make the more natural comparison).
The only drawback is that I found was that the volume attenuation was a bit ticklish. For some reason, I couldn't get it just exactly right. You can only control the headphone volume with the remote, and it's a digital thing ranging from 1 to 100. For some reason when it stepped up to the higher levels that I sometimes listen at, it began to sound strained. I'll try it again this weekend and report back.