Took me 20 years to get around to them and, bar one Steinberger, all my basses are Jazzes now. But Jazz pups - even stock ones - can sound different to each other, for several reasons I won't go into here, but what I look for in that rear pup (with the amp flat) is its ability to growl and to bring out those harmonics just behind the 4th fret and the ones just in front of the 3rd. If the rear one can't do that, out it comes.