I think that these techniques should be learned and then tucked away like a Swiss Army Knife. They aren't useful everyday, but sometimes there's an occasion when it's just the right tool.
PS- Ever try this technique? Works real good on the G string, say for the sake of argument at the 5th 'fret'
O-HO-PU-O-HO-PU
- that's open string, hammer-on, Pull-off, etc.
The open string is struck with a hard downard strike that turns into a pluck, the hammer on is done percussively with the left hand and the pull off note is your hammered note pulling into an open string again.
If you do it fast and strong, it has a cool sound like a basketball being dribbled. it kind of goes paTINka paTINka paTINka. Lots of fun and a neat accent that helps you find your position accurately before a solo, and is loud enough and interesting enough to mark the entrance to the bass solo. I use it rarely, but when I do it ususally works very well. Those little quirks are charming, but needless to say some cats just have nothing but gimmick, and that ain't cool. Heck, some cats just play too many notes because they can. Yuk.
-Con Trabajo