The default for some controllers are regen, which is not good if you are using a freewheel. My Kelly was and after I set it to coast, it was much smoother coming off the the throttle.
I just purchased the 750w mid drive kit from SBP for my old GT LTS. If all goes well, I plan transferring the kit to an 83mm ISIS setup for my Giant Glory.
My buddy broke a square tapered BB years ago and now all my newer bike have hollowtech BBs. Unfortunately, there are no freewheel cranks...