I,ve been toying with these a bit lately. I built a 27" wheel set with a ND coaster hub. It,s great fun. I think it,s more fun than myfixy but maybe I need to think about that some. It,s on a Schwinn Typhoon right now but that frame wasn't,t made for 27s. handles a little funky. I've got a diamond frame Raleigh that they'll go on when it's ready.
I've also got a 42 Roadmaster lightweight that's a blast to ride.
there's pictures of all this but I'm on my motherinlaws IPad thingy and I haven't figured out how to cut and paste with it.
not as versatile in the hills as a good old ten speed but really about the best thing for riding to the store with the kids in toe.