They race trikes ("barrows") in England. I understand they are very tricky to ride - most experienced 2-wheel riders will hop on a trike and start going around in circles the first time they need to turn. They can build them really light, so you can carry them over streams.
I've always thought a trike would be perfect in the winter, riding on snow and ice, except that you'd need some form of limited-slip differential so that you'd get drive from both back wheels. Otherwise, you're likely to be spinning the one driven wheel uselessly on the icy patch.
Anyway, good for you for adding some diversity to the cycling world. And yes, I have been known to ride a fixie on occasion...
Luis