Haven't had the pleasure to use them, RS, but Matt Pulcinella has been installing them on some of his basses as of summer, last year, and he jokingly recommends NOT getting them because he says they don't need a preamp, (i.e., he has to charge less).
He also says they sound deeper and clearer than P2 Barts w/preamp, don't sound "vintage" because vintage pups usually sound dead, (in his opinion), they are very much alive, hot, but not too hot, "just right."
It's a bitch there isn't some way to try pups out without committing to them, isn't it, (usually).
- I see sound
"Change the bass player, change the engine room." - Keith Richards
"Learn the rules so you know how to break them properly" - Dalai Lama