First off, I really don't care if you like Dime's tone or not, a lot of people don't like his tone... who cares. No one can deny that Far Beyond Driven is a great sounding album though, but to each his own. Second, you've owned 60+ Marshall Plexi's hey? (Do you own a Mansion and a Yaght too Elmer Fudd?) and only two of them needed caps? What did you just own them for a weekend or something? These are 50 year old amps. Any amp that old, if it is still stock should be going to the tech for a recap, especially the high voltage filter caps... if they are stock.
And yes, i've plugged into a few Plexi's before, I've plugged into many NMV amps in my 26 years of playing guitar. Never did I feel like I had enough gain with one though, and that's even with an overdrive. They're loud brash amplifiers that are basically obsolete these days. They've got one sound, well two depending if you're plugging in with a strat with single coils or a LP with humbuckers.
Comparing them to a 2203 or a DSL is not even fair as they do different tones. A DSL is a more modern high gain marshall, which is a tone a plexi can't get, so why compare? Apples and Oranges man.