IMO the Duncan Designed pick-ups were really bad. They had no detail, no color, no highs, no articulation, no nothing. They make even new strings sound dead. I changed the DD with a SPB-1 on a Squier VM Precision, and it was a completely different bass.
The key here is you're talking about the
precision pups. I've never heard marvelous praises of those and don't own them, so I can't comment. But the Duncan Designed
jazz pickups are really great pickups for an entry-level bass. They sound amazingly like vintage single-coils, and are
far superior to any of the several MIM jazz pups I've experienced.
And I'm not the only one with this opinion... Audere has some graphs buried in that website somewhere that shows frequency response of several varieties of jazz pickups they tested, including several boutique single coils. They also tested a vintage mid-70s US jazz pickup for reference. Of all the pickups they tested, only the Duncan Designed came close to the same frequency response.
Not that everyone here will think that the mid-70s Fender Jazz single coil pickups are the best possible pups, mind you. But they certainly aren't
junk. They're more like
funk.
Fender do indeed know to make great pickups, as in fact very very many other people do. But I think it was a great marketing decision.
Someone should tell the $600 Fender MIM people about those pickups, then. The ceramic bar pups I've gotten in the MIM Jazz basses I've had have been completely un-Jazzy. High output, which I'm sure makes many beginners think they're better, but otherwise pretty terrible. That's what was so great about the DD pickups in the VM J bass. They brought the classic J tone to the masses for a very reasonable price!
Granted, I haven't tried their replacements yet. Maybe they're as good, maybe not.