In the ladies thread about e biking the divide, I tried to put out reasonable, practical concerns.
One other Ive thought of is how someone using this stuff would really want to be able to troubleshoot any problem electrically wise, and hopefully fix it. If not, you're dealing with a heavy bike to pedal, and most likely, lets face it, the folks doing this will be folks who are weaker riders physically due to whatever reason.

and thats ok, just with the divide ride idea, or somewhere else far off, pushing or riding a heavy rig could very well be beyond their abilities if there was a problem, let alone simply if the battery ran out earlier than expected.