Some years ago I was sent to evaluate one for a potential UK importer, and was quite impressed. "Stretch" did a really good demo. A product surviving in that legal environment has to have something right, and we found the key was to get it built properly - indeed, I think they now prebuild a lot more now than they did then. Some people expressed concern about the belt drive tail rotor, but I believe a tractor belt drives the Enstrom (or is that an urban legend?).
I've not flown the Robbie, but I know people who have flown both and would go for the Rotorway, if it had doors.
cheers
phil