I think "YMMV" applies here. I don't get to dime mine, because I don't play in large clubs where a 100+ Watt amp can be cranked without hurting people. So its usually running clean, with pedals for added distortion, or using a Peavey Rock Master preamp for uber-gain.

At tolerable volume levels, I don't get tube rattle. None. And the tone is very flexible and adjustable. From thick 'woman tone' to Roy Buchanan-type icepick shrill. To me, Fender and Marshall amps are the one-trick ponies. The Ampeg can produce their tones, plus anything else you care to dial in.

If pure clean is all you want, get an old Roland JC-120. If you want something that will do it all, get an old Ampeg. As Bob says, his experience is different. I'm not about to call him crazy - I just find that my results don't match his. Or Ace's, apparently.