I suppose the 51 RI / Jazz pickup mod solves the problem I have with Jazz basses, which is that the neck's too thin. I wonder how that compares with the more obvious solution - putting a P neck on a J body?
the goofy headstock may be a reason for robin's bass failure. totally wrong imo.
I've found those 51 RI's to be surprisingly versatile stock. The real deal sounds better, but is more the one trick-pony. Matter of fact, the reason I don't have a 51 RI is that they don't sound 'P-Bassy' enough for me.