Check out Amy from "Clatter" (a killer bass & drums 2-piece) in Invalid Link Removed explaining her rig. The short version is that she splits her signal three ways to fill up the sonic space in being a two-piece: Clean Bass goes to an SWR SM-900 & an SWR Henry The 8x8", Effected Bass goes through a Boss VF-1 multieffects unit into an SWR Super Redhead 2x10" combo, and the Distorted Bass goes into a Mesa Dual Rectifier head and 4x12" Cab, giving her a huge sound out of her Rics and 12-string basses.
That being said, the reason that she goes through all that trouble is that the bass amps with various distortion wasn't "guitar" enough for her, but just the Mesa doesn't carry nearly enough low-end to fulfill the "bass" side of things. I myself run a dual signal clean/effected rig, and I could never imagine playing without my "bass" signal and cab. You can try playing through guitar amp and I doubt it would physically damage anything unless you maxxed out the guitar head, but from personal experience as well as talking to others who run in similar ways we've found *just* a distortion signal isn't very satisfying as a bassist.