I've been looking at Super Reverbs lately, mostly silver faces. The prices decrease with the master volume versions and decreases again with the ultra linear versions. I'm not worried about the MV versions, but tell me why I wouldn't want a UL version? From what I can tell, Fender started the UL super reverbs in '78. Is that correct? I'm looking for clean. I've got pedals for everything else I need. I don't care how much it weighs either. Basically, why are the UL versions less desireable than the others?