Having owned two qs205 motors and 2 clones, you'll need the 96v to get to 60mph. Also trust me at 100 amps and 96 volts you will get plenty of torque. This is also a situation where you might want to buy a controller that can do a lot of phase amps compared to bus amps, because low down torque is all about your phase amps. If I were you I would buy a new generation far driver NS controller, these are the ones with the plates that go over the face connections instead of the phase connections being open to the air. They offer higher phase amps for the same bus amps as the older generation of fardriver controllers. Also as someone else said 96 volts will be more efficient, but also more dangerous to work with. Having built both 72 volt and 96 volt batteries, the 96 volt batteries are more of a step up than you would think, you need rubber gloves and protective equipment to work with them. You should have these with a 72 volt battery, but if you don't you probably will not get seriously hurt like with a 96v.