It's a very usable set up. The jazz pickups in this bass were quite dark sounding and so is the Bart MM so I'd suggest getting pickups that have different tonal feels, like a vintage jazz ser and a modern aggressive MM etc to maximise tonal variety otherwise, as I found, the tones of jazz in parallel vs MM in series sound fairly similar.
That said, I wired mine up so that I could run any combination of the 4 coils and that allowed for some nice usable blending, the 2 neck coils etc.
I also think this set up works best passive with a switch or blend to go between MM, Jazz or both, that way you can have a tone control on each set so you can swap from front jazz tone rolled off to MM tone open and get big tone changes at my fingertips.
Praise and Worship Bassist #80 Rockin for Jesus!
Team Trace Elliot #11, 5+ Basses #39 BTB club #18