Carvin j pickups are bright and not as full sounding in the mids like stock Fender American jazz pick ups. If yiu want a warmer sounding bass, look else where. So if you like that modern jazz sound, it is a great option. Plus with being able to customize the bass the way you want it is another plus. Craftsmanship is just as good as anything out there.
I agree that the new pickup/preamp combo on the SB series basses is brighter than most Jazz basses. String selection can change things quite a bit, IME. The passive tone control along with the treble control on the preamp can also really change things up. Still, to get a mellower tone, probably the best option would be the H50 stacked humbuckers.
I'll echo the comments about customization and high build quality. That's a big part of the reason I own 4 Carvins.