One thing that hasn't been mentioned is the "sag" that the 101b has. You play through it, and it almost seems like the signal plays catch up when it hits the speakers. Not enough to seem like a delay pedal, but enough to notice that the "attack" isn't immediate, up front and in your face. When I jammed on my buddy's 101b rig, that was one of the first things I mentioned about it. I also saw in an early Bogner Helios vid that Prashant Aswani said the Helios was "Like the Blue channel of (his) 101b, but without the sag", so I can assume we aren't the only two who notice it.
The overall tone of the XTC amps are somewhat darker - which I really like, and lower-mid voiced, rather than upper-mids you typically find on Marshall style amps. Some people say because of this it's hard to cut through in a band mix, but I have not heard of that problem at all when watching my friends' band that has an XTC halfstack and a Fryette Sig:X halfstack. The Green/clean channel is rumored to be created in the same vein of classic Fender non-master volume amps, so to get the most out of it you have to crank the Green channel.
Experts please chime in and correct me if I'm not 100% on this.
One of my very few 'bucket list' amps that I want to own permanently is a 100b, but I think I would be equally as happy with the much more common 101b.
