Thumbs up on belt drive. I haven't so much as wiped mine down this winter, and have ridden in some pretty slushy/salty/nasty stuff. I swear the belt is impregnated with teflon or something-it stays very clean.
I tested by running a white cotton t-shirt down the belt and the shirt had minimal dirt on it, which was dry and dusty, not greasy and oily.

You can convert steel and Ti frames to belt drive pretty easily with basic brazing equipment: http://www.paragonmachineworks.com/s...-10731011.aspx
Such a conversion isn't cheap, however, when considering the fact that you'd need a new front and rear "pulley" ($200+ for both) and a belt ($50-70) plus the cost of the frame splitter ($35) and brazing costs / paint touch up.
AND, if you're currently running standard derailleurs, you'd be stuck with SS with belt drive or an IGH conversion.

You'd have a sweet setup, for sure, but it would cost you.