Thanks again Louis, that's very revealing about the Karr Bass!
It seems to be a very difficult and temperamental instrument to play and it is quite possible that much of Karr's method derived from playing this instrument. However, as most of us are aware, if you can develop a technique to produce a nice tone from a difficult bass, playing a more forgiving bass with this technique ought to be very rewarding.
From the very opposite direction, I have a good friend who studied music in college but dropped out. He has always played on a plywood King and a cheap bow, but he gets a great sound and always has. I definitely wonder what he'd sound like on a really good bass.