Stephen, I like your other comments too. I think Kreutzman referred to this as “the continuous one” :
From your post above: “ One thing the Grateful Dead learned as a band early on was the ability to set a tempo and feel, internalize it, and then let each member decide where the one is during a jam, the only way you can pull this off is if your inner clock keeps track of time without being a slave to it.”
And, “ Mastering a instrument should include being able to play in time but also learning to play WITH time to create a feel or atmosphere.”. Oh Yes!

I also like the comparisons of the Dead’s 72-73 spacey sections of Playin’ in the Band and The Other One with the stuff Miles was doing in the early-mid 70s (i.e., Live at the Fillmore, Bitches Brew, On The Corner, Big Fun…).
“feel your way, feel your way like the day before…”