Actually no I DIDN'T miss out on the difference. Although I haven't owned a RKII I have PLAYED one and my opinion of its crunch tones - EL34 or 6L6 - is no different. I also tried many varieties of EL34 in the Roadster and again - crunch tones nowhere near what the XTC can do - and BTW my XTC is the standard 6L6 20th anniversary version!
I think the whole progressive linkage thing is a bit gimmicky, to tell you the truth. There are other things which make a much bigger tonal difference than power tube type.
Makes a big difference on mine.
Look, I'm glad you dig your amp, I just didn't care for it nearly as much as I do my RK, it just really didn't impress me all that much, particularly at that asking price, sorry.
Maybe it had something to do with the fact that the one I played was right next to a Diezel Herbert that made it sound comparatively weak, IMO.
I'd still love to check out an Uber, though.
Different strokes...