Well, if you load up a black hole with, say, electrons, it will have an electrical field similar to a point charge -Q, just the way the mass M behaves as a poin

Well, if you load up a black hole with, say, electrons, it will have an electrical field similar to a point charge -Q, just the way the mass M behaves as a point mass emitting a gravitational field (or distortion in spacetime, take your pick). Additionally, when you get Hawking radiation into the mix, negatively-charged particles (electrons, muons, tauons ... but probably mostly electrons) would be preferentially emitted, since pair production near the horizon would preferentially eject the negative particle via electrostatic repulsion and just as preferentially recapture the positive member of the pair. Not that you asked, but the angular momentum looks different than the other two, it actually changes the shape of the event horizon to something more oblate.