I've been playing this lovely thing a great deal. I've gone through a load of different strings to see what I like on it too.
One thing I've really noticed is that when it was just a P the B could be a bit crap with the wrong strings, particularly flats. The B would be flubby and not have the same tone as the other strings. D'addario Pro-Steels sorted that out perfectly but I still wanted to do a Duck Dunn thing for the big band.
The new J pickup has cured that flub even with low tension flats (La Bellas). I suppose the J is just sensing the string at a point where string movement is a lot less.
It's definitely not the Duck way of getting that tone, but I've got the J at full volume with the tone backed off to about half-way, and then I ease up the P to taste.
"Shake a tail feather" now sounds bang on.
Summer Concert is on Saturday and I'm looking forward to it!