Like others I have been researching E Bikes a lot. Where we live we are surrounded by hill so to go anywhere you have to get up a steep hill first and with my knees that results in a lot of discomfort. On the flat and gentle inclines fine. A year ago I had bought a new Hybrid that I like but we had to travel to get any enjoyment and as I said hills were a no no. I didn't want to get another bike and resale values of bikes are low. So I took the plunge and converted mine. I know a hub motor might be the best but I wanted something simple and so I went for this:-
http://dillengerelectricbikes.co.uk...bike-kit-samsung-power-13ah-by-dillenger.html
Came quickly, good downloadable instructions, easily fitted if you can make simple adjustments on a bike and worked straight off, with Pedal Assist or throttle. Controllable top speed setting and Brake operated cut-out.
On test runs it coped with all the hills out of our town easily including a very steep local hill which is difficult to walk let alone cycle. All in all very pleased and I keep my hybrid bike as well.