I have test ridden (several years ago) a several bikes with Impulse motors and was not at all impressed with the assist. One was a Kalkhoff that looked similar to the one in the photo above - rim brakes, battery behind seat tube. The other was a Focus class 3. These 2 bikes put me off 'off the shelf' mid-drive bikes. But then I rode Bosch equipped bikes and the difference was night and day. It's amazing how they get such a snappy feeling out of 250 or 350 watts. I have not spent lots of time on Shimano Steps or Brose equipped bikes (but I've ridden them), but thus far, my experience is besides the noise, Bosche gives me the preferred feel. As for the old Kalkhoff with Impulse - not enough assist and too big and clunky.