I heard Wave That Flag before I ever heard US Blues. First Boots were 2/15/73, 2/13/70 and 6/10/73. Then my grandmother thought she was being hip by giving me Steal Your Face for Chanukah that year(1978). I remember even then that the tapes sounded better then the Album.
Speaking of evolving Dead tunes, I'm listening to a righteous Main Ten jam at the moment and (in Spicoli voice) "..it's like it's Playin in the Band, dude, but like only it's not." Seriously though, listening to all these songs evolve is fun indeed.