As Flecc said, I've had my 350W Bionx some time now and am just as pleased with it today as I was when I first bought it, though I think I paid about £1000 for it, and already had a Trek hybrid to fit it to. My wife's bought one too but not used it as much and has a problem with the torque sensor, which NyceWheels will sort out under guarantee but of course we have to pay postage, which isn't cheap unfortunately. I think it's 'one of those' things and would certainly buy another but £1400 is pricy.
The battery life isn't as good now, but then I've fitted fat Schwalbe Marathon Supreme's whereas I used to have much narrower Continental Sports Contacts. Also, I now ride with big panniers and notice a difference with these, just with their wind resistance.
The only bike I've seen that would seriously tempt me away if the Cytronex but John seems to think the performance isn't as good - time for a new thread, just out of interest as I'm not interested in knocking other setups or choices.
Good luck with your decision.