This bike booster will probably come in at less than half the cost but the Bimotal kit is another option that doesn't have the tire wear issue, offers better performance, and the form factor is much nicer.
As a mountain biker I don’t see the appeal of this. Yes, this rather expensive solution could transform my nice bike into a shitty e-bike, but the point of having a nice bike is to avoid a shitty experience.
A proper e-bike needs to be designed as an e-bike from the beginning.
Wow, $2k? You could get a decent ebike for that money. And the installation doesn't look any easier than a hub motor... Only seems worth it if you already have an extremely nice bike. I think of friction drives as being aimed at budget-conscious commuters, not serious mountain bikers.