I don't know about phantom powered pickups, though it's a great idea.

I've had Washburn, homemade, and Godin electric basses with active (nine volt) electronics and found them acceptable, but all in all I prefer passive pickups and floor mounted pre-amps and volume peddles. I have one acoustic guitar remaining with an internal Miniflex mic run by a single AA battery, but I still use a floor preamp and volume peddle as there's no controls on the instrument. I've grown to prefer the controls on the floor so that I have hands-free operation. All my other instruments have either passive pickups or none at all.

My thought is that there's no reaching inside the ax for battery changes, the floor units will work with many instruments (I use an a/b box and a small mixer too if needed), my preamps have a much wider degree of control than the typical guitar installation (I use Boss EQ units, George Dennis volume peddle, Berringer mixer, Digitech RP200 multi-effects unit), and the whole thing is easier to repair if needed (even if it's more to carry around). Battery changes are easy, though the whole thing can be wall-wart powered, and the mixer will supply phantom power to a mic if required.

Someday I'm gonna build a custom pickup with a soundhole humbucker and a mic (a la Fishman Blend), stereo output, with my usual outboard controls. Please forward cash donations asap.

Peace. Mooh.