It could be used for bass - yes. But one thing you need to consider is the frequency range of this pedal - versus what is good for a bass....
As for vocals given the right DI's I guess you could but my understanding is that you would need something that ran at line level, or could convert the mic to guitar level inputs if you are playing through an amp..
Look around the squillions of boards though - there are many people who are not completely happy with GE-7's for guitar let alone any other, more esoteric, application.
PS Yes. There is always someone somewhere that hates some piece of equipment </end disclaimer>