You know, the first time I saw a live jazz band was a real shock to me. It had never dawned on me that, with the solos and all that there were times when musicians were doing absolutely nothing but standing around with their thumb up their ass in the middle of a song. When I saw the tenor player standing there nodding his head, then scratching, then appearing to search for something on the stage floor, I found it totally distracting. So I probably would go with the "yes, please leave the stage and get out of the way if you're not playing" vote. I think what bugs listeners who aren't used to it is the idea that a musician isn't concentrating totally on the music being played from start to finish, but eventually we figure out that jazz is even more different than we thought...