+1. I just put riser bars and MTB levers on an otherwise stock Schwinn Caliente for my girlfriend to use as a campus commuter (hey, if something's going to get stolen, it might as well be a Caliente). The brakes work just fine.

V-Brake levers may be a different story, though. If it were me, I'd try some non-V levers with the brakes you're currently running. You can get an economy pair for $10-$15, much less than swapping out the brakes.