If you gear your elevator correctly, you should have no problems relying on stalling the motors for short periods of time. I wouldn't see any need for you stall your motors for extended periods of time great enough to cause any negative effects.

Can you describe the power transmission system for your elevator (motors, gearing, etc)? I'd be more than happy to help get your system so that you can safely run at stall, which would save both weight and possibly time.