I have 2 fretless bases with EMG P/J set up
Both basses are custom built. Both basses have the bridge pickup mounted about 3/4 of an inch closer to the bridge. Pic can be found here. http://www.myguitaronline.com/pics/Twins.JPG
One is a spalted maple body with maple neck and ebony fingerboard. The pups are accompanied by an EMG 3 band onboard preamp. (BQS) I have the X version PJ set up in this bass. The P pup is also moved 3/4 of an inch closer to the bridge
The other is a walnut body with a maple neck and rosewood finger board. The pups are accompanied by an EMG 3 band onboard preamp (BQS). I have the standard PJ set up in this bass.
The difference is quite startling. The maple bass is terribly punchy. It works really well for funk. The walnut bass has a much fuller sound, and works well for traditional Chicago Blues. The bad thing is I can't decide which one I like better.
It's much easier to get that "Jaco" sound with the X series pup
I play in a couple different blues band. We play in small to medium size venues, so I'm usually dialing in the tone looking for the sweet spot at every differnt venue. The x series is a little bit harder to dial in.
If you have any other specific questions, let me know. I'll try to help