The other option would be to find a front suspension mtn. bike where the fork has a lock-out feature. That way when you are going to be dirt riding, or doing a lot of curb hopping, you can engage the suspension, but when you are riding on roads for distance, you can cut it off so that it doesn't leech power.

Just a thought. Without some suspension, if you are doing a lot of jumping or rough riding, you could have a lot of trouble with the wheels getting out of true.