I think that the front hub motors are fine in the 250 to 350 watt range, not enough power to be much of an issue in turns, loose surface, plus you can use your coaster brake. I like the mid drives as opposed to rear hubs because of the gear range, rear hubs are pretty much limited to single speed. Batteries ARE were the money is. Luna & Hilltopper both offer quality batteries. I think that I've learned more from Karl Gesslein's Ebike blog than anywhere else. He does favor Luna. Shipping the batteries is getting easier. I recently shipped one to Colorado via UPS, it was pretty easy, you just have to declare, pay a little extra & put a warning label on it. As far as swapping batteries from one bike to another, a 250 watt motor uses a 24 volt battery, 350watt, 36 volts, 750 watt, 48 to 60 volt battery. 60 volts kicks the motor up around 1200watts & not sure how it will fare in the long haul. I use 12 volt batteries in series on a couple of bikes.