Fred, I agree what you say about James Cotton. He does have a restraint to his playing. I think now that he's getting on in years he probably isen't doing back-flips up on stage anymore! As a matter of fact he isn't touring much anymore these days.
I just watched a documentary on John Lee Hooker and it showed quite a bit of one gig. On stage he had Charlie Musselwhite and another back up harp player that I didn't recognize but the two sounded good together.
That you don't see happening too much, where you have two harp players on stage. Last year I did a blues fest and my friend and guitar player and I did a harp duet together that was nice. I think we did "Got my mojo workin'" but I'm not remembering for sure!
Rustic