I've had a Marcus Miller CIJ Jazz and it was quite a nice bass, apart from the awfully harsh sounding preamp. It sounded reasonably classic jazz in passive mode (but there was no tone control in passive as mentioned earlier in this thread), and the best sound I had from it was to run it passive & put it through a Sadowsky preamp/di pedal.
I actually ended up selling the bass to fund another Status bass, but now have one of the new American Standard Jazzes running through the same Sadowsky preamp. The sound is utter heaven. Rich, rounded, as much top and bottom as you want & thunderous. Job done
Oh, and the biggest downside to the Marcus Jazz is the weight of the thing. It weighs more than the Queen Mary!