Another big issue is stealability - as a cycle commuter I considered an electric conversion right up until I remembered my office is in one of Oxford's black spots for bike thefts (the whole area is bad to be honest, but I'm in one of the worst places for it). The key to preventing your bike from being stolen by some fifth generation product of inbreeding isn't to have the best lock, it's to make it less worthwhile to steal than the bikes around it. The crappier your bike looks the less likely it's going to be stolen, an obvious electric bike parked with any regularity is going to vanish pretty quickly to a thief with a bolt cutter no matter how good your lock is.