One of my local bike shops has been pushing (well, metaphorically, I mean), the Giant Full-E+ 1, which looks like this:
It’s an XT-level mountain bike with dual suspension and disc breaks, and I have no trouble with that. 2.6″ tires, which are pretty much the norm nowadays, and a Yamaha motor that puts out 500 watts. Surely, nothing can go wrong there.
Yes, I know, there are times when having extra power can get you out of a jam, and to get the fun of riding downhill you typically first have to ride uphill, which can be a drag. But among the complaints I hear from people on mountain bikes, “doesn’t go fast enough” has never been mentioned, not even once. And given the propensity of mountain bike riders to endo even under their own power, I’d hate to be the insurance company that stands behind Giant or its dealers.