I began ebiking with a 9c hub motor, external controller and HK liPo blocks. Now Im running the BBSHD hot-rod with a 13.5 Ah shark pack. The difference is night and day. No more rats nest of wires for the batteries, no more charging each individual battery for every ride, no more weekly wheel work! The motor is whisper quiet, powerful and sleek. Most people don't even know its an ebike unless they look closely. The cons of this kit? Shifting is hard unless you let off the throttle/pedals for a solid second or two (getting the shift sensor), The stock chainring is ugly and way to big for anything but road use, and I had to drill through the battery mount to fit it on the frame (watch the video on the shark page). Included ebrake handles wont work with my hydraulic brakes.
I'm getting 34 mph on flat with the throttle only with the Luna one 36t chainring, 11t rear on a 29" wheel. The c961 display is ok, nothing great. No Ah used option, just a graphical battery display, not sure if its accurate at 52v yet.
All in all, 5 stars. This is a fantastic alternative to over-priced showroom ebikes.