Am I Unhappy With Bartolinis, Or Just This Model??

IMO what you described is the bartolini sound,clear,clean,almost sterile.
They work for me only on agressive guitars you want to smoothen out.

 

how are MK5 wired? from what you describe they could be in parallel, and wiring them in series might suit your needs better. if they are in series already, you may have to consider another brand. I had an opportunity to compare the same bass with MK1 (reversed P) and MK5 (wired in series), and while the sound was similar in a way (you could tell they share some heritage), the MK5 were far superior in dynamics and had a bit broader frequency range in both directions. both had similar response to the onboard preamp, however where MK1 compressed the sound when digging in, the MK5 would bark.

reverse P is a mirrored P. on a "normal" P you have the upper (EA) coil closer to the neck, while lower (DG) coil is closer to the bridge. this is reversed in a reversed P.

 

Mk5 cbc I have in my Lakland are quite polite. I have the original split and a deep tone music man Bart in my custom build which give me a little grind if I dig in (I play flats so a little is the best I'll ever get).... not sure if it will be enough for you

Try raising your current pickups closer to the strings if possible, the wiring change suggested above is another good idea that won't cost anything

If you do decide to change them out
The mk5p model should also be on your radar.
As to the the tonal difference between them (split p bass in a soap bar) and the original split model - I'm curious to find that out myself

 

A different Pre-amp might help.

 

The Mk1's will have more "focus" compared to the MK5 because of the coil design. The Mk1 are essentially a split coil j pickup with the bass coil closer to the bridge and the treble coil closer to the neck. This tightens the bass response while opening up the upper strings. It sounds like you prefer the narrower tone print of single/split coil pickups over the much wider dynamic range of dual coils. You can actually have the xxP25c (or xxP25cx bright wind) wired for p/quad/reverse p so you could switch btwn them all till you find what you are looking for as well as have versatility.

 

Can you share a little bit more about your setup? The preamp you've got in there, etc?

I've got a number of basses set up with Bart CBCs. Huge sounding, yes, and all can get punchy and percussive.