Cranshaw switch to a upright bass is for musical reasons only. The last couple of time I've heard him he's played a upright. Bob may have had back problems but I believe that he played the fender for such a long time because that what was called for in his studio work, and he stuck with it.
These day, like others, he has the venue provide a acoustic, or sometimes he travels with one of the hybrid jobs. He can do whatever he wants, as far as I'm concerned.
I'm glad that Sonny got rid of the dreaded percussionist. His nephew the trombonist didn't bother me much, as most of the guitarist he's used. I loved Mauso! I have no idea what happened to David Lee ( who also played with Dizzy). It's a mystery.