My 2 cents... Until recently I worked at a Bogner dealer, and I have owned a 101b.
I think the XTC has a Bogner flavor, but it doesn't nail the Bogner. It's never going to with the different power sections.
I have played the Uber many times, at gig levels as well.
Personally I would rather own my Randall, or the MOD50/100 if I had the jack. They both punch better through a mix in my opinion, and have a more percussive feel.
I find both the Bogners to be too compressed for my taste, particularly the XTC. But other guys sound great with them, a couple of my good friends own Ubers. GREAT build quality, and a certainly very strong characters tonally, and Bogner is fantastic with customer service issues.
I hope this helps in some way, they are great amps, but not for everyone.