I own a prototype, that I recently reverted back to factory specs (Bruce Egnater was kind enough to provide the schematic... 7 pages!)
It seems to be very picky about tubes... or maybe I am. I got channels 1 and 2 right where I want them.... great clean/slight breakup sounds.
I actually put it up against an Uberschall and Mesa Stiletto the other day... played through each about an hour through the same Bogner cab, and ended up preferring the Vendetta. That might have just been cause I know how to dial it in though... and I'm still learning new things about dialing tones with it, even after 1+ years!
As for distortion lacking... I never had a problem with that. I have to say though that I don't do uber saturated. I can do Rhapsody, Iced Earth, up to Blind Guardian without problems... it won't get you
the Killswitch Engage tone though.
That being said, I've been trying to sell mine for a couple months now... no buyers.
I switched to a rack rig, GSP1101 + H&K Access + Multivalve + DHP-33 + Marshall 8008 into full range wedges. Reason: college. I can even practice with headphones and get a great tone now though.
Hope that helped!
E-mail me at eleanor296 at hotmail dot com if you have any more questions.
Andy