Well, I'm probably a little late to the party, as there seem to be threads about the floating thumb technique all over the place now but....
This morning I was browsing youtube and ran across this:
http://www.youtube.com/watch?v=PPVMBPmrblU
I'd never heard of Todd Johnson but it appears he's a virtuoso jazz player.
Anyway, I have always had severe trouble with ascending lines on anything with more than 4 strings. So I had a go with this technique this morning on my L2500 fretless and saw an immediate and very dramatic improvement in my ability to play ascending lines as well as mute strings when ascending.
I attached a .mp3 of the beginning of a new song I came up with while practicing this.
Anyone else learning this floating thumb technique? Any pointers for practice and etc.?
LS