Now that I am interested in electric bikes I visited a dealer on the Isle of Wight as we happen to be there. He specialises in MTB electrics. I tried one out, top of the range job. Quite portable, with the batt in. Entirely torque based response system, and it was a bit of an eye opener. Silent, light, and responsive, just like riding but very little effort. Costs £2300 though. The motor was built into the BB very neatly and batt likewise. He also had a road bike with batt in the down tube and rear hub motor almost invisible. Awesome kit, really.
Apparently about 60 miles range.