I'm afraid I'd have to agree, that's a little 'steep' for a sweep tube amplifier, at least for me. Don't think that I'd want a multi-tube amplifier unless it was just too 'reasonable' not to turn down. (Been there, done that, just not worth the trouble.) Also been the 'SB-220' route. Depending on the particular amplifier who built it and how, an 'SB-220' is a pretty nice amplifier. There are things/mods that make it a much nicer amplifier though (the 'Measures' mods). Still a multi-tube though.
Single tube amplifiers are just easier to maintain, less complicated, will do almost what any multi-tuber will do. The differences in power just aren't worth messing with usually. Then again, using just 'gobs' of power isn't necessary in any reasonable circumstance. In unsusual circumstances maybe, but those really are few and far between.
I guess everyone ought'a try it once. And when you get your fill of it, get back to something reasonable.
- 'Doc