Not sure how I stumbled across this long nascent thread, but I enjoyed reading your contributions. Since I know we share a common obsession, I wanted to add one thing. I believe this is from Levon - he said that Richard Manuel played rhythm on piano and melody on drums.
Garth on piano, Levon on mandolin, Richard on drums was equally as great as Garth on organ (heck, on anything), Levon on drums & Manuel on piano. After 50+ years, it's still a 3-way tie for favorite vocalist, too.