I purchased the 30k kit because I wanted a lightweight 250 watt motor and battery. My intention was to keep my Electra Townie light and ride-able without the motor and to use the motor as a “helper” for hills and wind to keep it fun. What I have found is that even on flat ground I enjoy peddling using about the same effort as without the motor but cruising at 18 to 19 mph. I peddle from each stop help get up to speed and can cruise at 16 to 17 mph with no wind on flat ground and I weigh 210 lbs.
The bottom line is that I really like the kit as it is a perfect kit for keeping your bike light and making it fun and easy to go for a bike ride without worrying about the dreaded wind and small hills. If you are in very hilly area and a bigger person you may want to consider a bigger motor and battery but that will cost you in the ride-ability department.
So there is my .02 worth which may be over priced… 🙂