Here is another unicycle made to give you a smooth ride. The SuperRide Self Balancing Electric Unicycle (S1000 G2) allows for speeds up to 20 miles per hour. It charges from 20 to 100% in an hour. You can control by learning forward/backward and using your weight to turn.
This unicycle weighs only 45lbs. It has a range of 15 miles and can handle max load of 280lbs.