Right now MM has to play catch-up to MP, IMHO. MM is clearly the technically superior drummer, but that often means jack shit (Rusty Cooley, anyone?). MP in the 90s was the plain leader in prog drumming, and I'm not sure MM would have walked the same distance.
Then again, it's also very clear that MP was very lucky to have the musicians around him that would enable him to walk that distance. With AM he fell flat on his nose.
To me it's the classic "what if" scenario in history. We will never know.
rumborak