Hope I'm not overdoing my experience with a new mid-drive kit, but seems as though it would be applicable to commuters. Just completed a build with a Revel Propulsion mid-drive. The kit added 12 pounds (10 for the motor and ancillary parts and 4 for the battery, while replacing slightly more than two pounds of crank/BB). There are several nice things about the system beside the fact that it closely resembles Yamaha and Bosch OEM's in performance. These include, but are not limited to, switching from 20 mph assist to 28 just by pushing a button on the display, motor nesting very close to the down tube, not hanging down like a cow's udder, very good instruction manual (on website) and nine utube videos to facilitate assembly, ease of mounting/ removing battery, connections are waterproof and no spaghetti (preponderance of wires that must be dealt with).