What do you check first before choosing an e-bike conversion kit?

[gromike]

My favorite bike that I converted is a torque sensing direct-drive rear hubmotor (Grin All-Axle) with a Grin phaserunner controller at 52 volts in an old dual suspension mountain bike. With a dual acting (accelerate/decelerate) throttle it's just too much fun on motor power.
It pedals really well, but, well, a quick motorbike makes one forget to pedal.