@ezwind , @goofyfoot
Interesting how our perceptions differ. Keith’s background was actually in Jazz. I very much hear him as a chameleon. When Pig Pen sang one of his Bluesy tunes, Keith was there with the stylistically appropriate parts. Same with Country tunes such as You Win Again or Sing me Back Home or Jerry Lee Lewis style riffing on rockers like One More Saturday Night or Sugar Magnolia. However, when it came to the more exploratory, spacy stuff, he also responded appropriately. He most certainly did not play Boogie Woogie on those tunes or on the modal, Fusion influenced material from Blues for Allah. The further the music strayed from basic Roots styles, the more clearly I hear the jazzman in him step to the fore.
On this same topic, Garcia changed quite dramatically. In ’71, ’72, his playing was stylistically much more diverse. On Country tunes, he employed the traditional vocabulary of Country players. Ditto with Blues tunes. On Johnny B. Goode, he played the hell out of the Chuck Berry licks. When they played The Other One, Dark Star or PITB, he utilized his more abstract, atonal, psychedelia bag of tricks. By ’77, he’d shifted quite a bit in his approach. He was much less constrained in terms of adhering to each particular tune’s style/genre. Without going into music theory, you could say he "just played Jerry". At least, this is how I hear it.
I’m not a pro player but have played guitar for 50 years and this has no doubt influenced how I listen.