I took a listen to Peace of Mind for the first time -- I never even knew it existed (shows how little of a "Beatlemaniac" I am). I'd have to say it sounds like an equal collaboration between John, George and Paul. There are quite a few moments I can hear George's voice predominate, and a couple with Paul. I think they collectively decided one day to noodle around with some off-the-wall Dadaist John Cage experimentation.
While I applaud the intention -- I think it's always cool to push the envelope musically and experiment -- it doesn't mean the finished product ...