I've only seen them used for lead or bass work. I can't imagine comping on one, especially at that angle. I guess if you're a real "mobile" type of person, you may enjoy the aspect of being up front with the singers and such, but as a player, you may miss some of the technical aspects of your routine. I suppose you could just have it handy for solos, and play a stationary rig for the tough stuff. Is that along the lines you're thinking of?
At any rate (how about 10% ?
) the Roland AX-1 is a popular model, and Casio made one that was pretty affordable a few years back.
Good luck with your new band.