hardcore -useing a higher voltage as a boost type setup can work well, ive done it with relays on the fly for say double the power , then you switch back for economy, its something electric vehicles can do very well. think of all the motorbikes around with 100+kw and 90% of the time they only use 5kw!
Bikemad -i didnt widen the wire slot at all, just used thin ribon cable for the halls and just separate phase wires, without a cover over the lot, needs a little care not to pinch wires etc.
it has about 44kg of pulling (towing) force at 5kph and the bike weighs about that so it has the torque to get itself up a 90deg slope! but im 90kg so might be about a third of that (30deg maby) with me on the bike, safe to say there are not many "normal" roads too steep, and thats without pedalling.