More on the octave-coursed eight string
here- Hagstrom were the first manufacturer and I think JPJ has been playing eights and tens just about since they were first made.
As for the extended range bassists- technically it's fantastic, but I find two things:
-firstly, I even avoid the skinniest string on my four string because the guitarist is taking up the same space, so half of those ten strings would be difficult to use with a guitarist or pianist around
-secondly, a lot of it is technically brilliant but of questionable taste. Most of the bassists that people are still talking about fifty years on ( Jameson, McCartney, Kaye) are technically competent but almost never flashy- Jameson didn't even alternate fingers when plucking. I think restraint goes a long way on bass