Does a lower wattage hub draw less of the charge to make it last longer? (also given the same terrain, say FLAT with no wind, the same bike and rider)) In other words would a charge in the same battery go further with 250 than 500 watts? I'm sure it would not be double, but I'm guessing that it would go farther but not as fast. Thoughts, opinions, controlled studies ??? post-script- wouldn't it be great if we could swap out a spent bottle battery at a bike shop or a convenience store like a propane cylinder, and just keepin movin on down the road? I think they may do that with electric car cells eventually.... and I hope the price of batteries comes down!