I took the FreeBSD plunge yesterday with a purchase of the full 4.8 (Stable) developer edition. I plan on installing the OS, plus I plan on compiling the Rotor code (the docs say that it has been compiled and tested on FreeBSD 4.7).
This is, of course, entirely a recreational activity, but I should learn something in the process as well. I will write more about my experiences as I go along.