Thanks for the tip. If it were my bike and not just a loaner, I'd seriously consider that.
Went for a 39 km tour on Friday. Didn't push hard, just nice and steady. Knees ached a little by the end, but it's hard to say whether that's just me or the bikeE; I don't do 39 km rides on my regular bike, so I have nothing to compare it to.
Aside from being tired at the end (I'm not in particularly awesome shape), I can say that my butt/back/neck were NOT sore at all. And that riding the BikeE is much more condusive to sightseeing.
I'd put a fairing on it though.