I saw Leon on tour in the early '80's and he shared a stage with Edgar Winter. I can't find any evidence that they played at the Front Row Theatre in that time frame but my time guestimates are never far off. Perhaps it was a one off type show and not a tour. Regardless, I wish I would have seen him more than once.
Carney is an odd listen. Leon is one of the few artists in which my favorite album is a live album.
I think people like Leon Russell, Warren Zevon, and Randy Newman.... who get overlooked at times... are 3 of our greatest American songwriters.
I would replace Warren Zevon with Harry Nilsson but yeah, Leon belongs there for sure. You are right about singer/songwriter types getting overlooked by the mainstream. Here is a sad example...a guy I work with knows what Elvis Costello looks like but doesn't know his music. He thinks Elvis is a novelty act like Weird Al due to his funny glasses. People are stupid.
Ever see Leon Russell's acceptance speech at Rock n Roll HOF? Total tear jerker.