Hello Trakker,
I have just purchased one of these kits. For a similar reason to you. I came down with an attack of inflammatory arthritis Christmas 2006 and so have not much strength in my ankles, knees, hips, wrists and elbows, but wanted to get back on my bike and get some fitness back.
I wanted to use my current bike due to it's very high quality, familiarity and lack of storage for another bike. I looked at lots of options but decided, as I was unsure if an electric bike was for me, to limit my expenditure. Though there were a few must haves, light weight was one of them.
My favourite money no limit would have been the Bionx.
I initially had a couple of difficulties with the kit the first was that the shape of my forks interfered with the motor, so I had to swap for an older set. The second is that my shifters hit the throttle housing so I have currently have them off-set inboard about 2 cm on the handle bars.
My first ride were a little disappointing as it seemed to stop assisting at about 12 mph, a little below my cruising speed, though it obviously still helped me up the hills!
After talking to Bob at Alienbikes it turned out that mine had two wires connected and this put it into economy mode. After disconnecting it really flies now!
Bob has been very helpful throughout and always saying if I was not happy I should send it back and he would refund me without question.
I am now very happy with this kit and I have cycled thirty miles in two days and for someone that has not been on his bike for just over one year that's not too bad. Don't forget we have some pretty nice hills here on the Isle of Wight.