Have a look at the Bafang Max Drive, not to many around at the moment, although the Greenway model on eBay seems to be selling quite well at around £1000.
More oomph than the Bosch CD models, and no need for a dongle as assist cut off restriction can be removed with ease.
Rumour has it that Halfords are soon to release a CD ebike, my guess is that it will be using the Bafang Max Drive motor.