How is a 25kph scooter any worse in traffic than a tricycle? Sure, I'd try to pick a route that avoided the Derby ring-road, but many of us ride trikes in urban traffic and can attest that it isn't instant DETH (indeed, if anything, it's safer than a bicycle, as you're more likely to be seen).
And yes there's a fundamental difference in manoeuvrability between a scooter and a bicycle: A scooter has a tighter turning circle and a stall speed of zero. I'm not sure why that's an argument against the scooter. Presumably anything built to do 25kph would be designed to not be hopelessly unstable at that speed, and like any other vehicle, you slow down for corners. You see people using such things in the Netherlands, and the technology appears to be a solved problem. What we need is more appropriate infrastructure, and the legal changes to allow scooter users to use it. A scooter user on a cyclepath is one less car.
