I got in a Pisgah Mountain ride Sunday on an early pre-production model of the Tomi-Cog. Gotta say it was hiccup free, and it will be well worth the money if you're looking to try off-road fixie on the cheap.
Pics and....
http://teamdicky.blog.com/2459292/
Video:
http://teamdicky.blog.com/2454116/