higher action = better tone, once it was my idea too, but now I've radically changed my mind.
It's all about touch. My mind was changed by a great italian jazz performer whom I told the same thing:
"when I want to give a strong dynamic to the sound or just being crazy at y gig my bass play worse with a lower action".
He told me: Federico, I know you teach martial arts. When you do that, do you teach your pupils to hit strong? or to hit fast and precise in order to get the most effective result?
I said, exactly the second one.
He said: when you got expert it's kind of automatic to give fists and kicks fast,precise and bloody effective even in the worst situations. Thus you forget how to be brutal.
I said: you've got the point chief.
I spent days doing just one silly but effective exercise:
left hand laid on the fingerboard in rest, muting the strings.
Right hand. Put your fingers on a string. Prepare yourself to hit the strings. Focus on being as much fast as possible. You won't have strenght on your fingers because they'll be already laid on the strings. Focus focus focus and then hit! repeat,repeat,repeat.
Have you seen Kill Bill when Uma tries to escape from her cuffin? =D well same idea.