We seem to be having one of our scare stories in the UK again, that demonises E-Bikes that are a bit too fast.
http://www.bike-eu.com/Laws-Regulations/Regulations/2014/10/Speed-Tuning-Kits-Threaten-E-Bike-Market-Development-1630453W/

Didn't we do this 5 years ago? And has UK gov yet officially synced UK law with the EU? Is there an official testing method yet to prove 
compliance? Has anyone been successfully prosecuted for using an 
illegally powerful electric assist bicycle on the road?

And note that the USA copes fairly well with 750W-20mph regulations so 250w-25kph seems pretty wimpy. And a couple of European countries manage an S-Pedelec class with much reduced regulations compared with mopeds and 125cc M/Cs.

My own views are very simple.

If it looks like a bicycle doing bicycle type things, nobody will ever 
notice or care. Even if (and I hope you don't) you have an accident 
doing them.

I don't especially want commercially available E-bicycles that do 25mph with 1kW of power without a licensing regime to go with it. However a 15mph power cut off does feel a little low in some circumstances as does 250/200W. The problem is that unlicensed use has to include a pensioner in heavy traffic doing the shopping as well as a downhill enthusiast.

What I really would like though is some mechanism whereby light electric motorcycles, trikes and quads can be easily road registered, especially for home builts. I'm not entirely sure what form this should take. We do already have SVA and that works pretty well for kitcars and custom motorcycles. It just seems like overkill for a 50mph E-Velomobile or an E-Moped or such like. So let's have a debate about that, rather than demonising E-Bikes that are a bit too fast.