Dave, I had a Haibike XDURO 29er for about a month this year and it was excellent. The Bosch mid-drive was extremely responsive and the torque sensor provided power as long as pressure was on the pedals, so the power delivery seemed like I got stronger, not had a motor. Everyone that I let try it, loved it and at least one purchased a Bosch-powered as a result. They have refined the system this year and 2017 models will be even better (BTW, I'm not affiliated with them in any way).