The Zero XU is a low powered motorcycle.
14 kW motor, 2.6 kWh battery pack, 200 lbs. 42 miles range at 30 mph type speeds, 65 mph top speed.
The Audi ebike is a really nice electric bike.
2.3 kW motor, 0.53 kWh battery pack, 46 lbs. Claimed 31-44 mile range, likely at 15-25 mph type speeds. 31 mph on motor only, if that's power limited then there's no way you'll reach 50 mph with pedal assist. An extra 500-700W from a human cyclist pedaling pretty hard won't get you there, if the motor is actually putting out 2.3 kW.
Anyways.. at least range anxiety is gone, if you run out of range you just have to pedal a slightly heavy bike home : P Also, that headlight rules.