To answer the original question, no, not yet but was very impressed with the electric Brompton when I tried one a couple of years ago. If I could justify owning one I would be tempted but for now I am going to keep getting a work out on the hills. Where I live there is a steep hill which I end up doing 3-4 mph by the time I reach the top but my neighbour, who is older than me and not a regular cyclist, gets up the same hill at around 13mph - electric bikes seem to flatten out hills.
One problem round here is the lower orders are latching onto these seemingly unregulated (in every sense of the word) electric bikes as a means of transport. I have seen some pretty awful behavior on the roads by these oaf's on overtyred and overpowered electric vehicles. This will no doubt generate a moral panic and then we will end up with some ill considered draconian regulations which would be a shame.