I am not sure who knows about this free program but here goes...

It is a Japanese program called hamaPatch (sort of like sPatch on steroids!).

Features: Many!
Renders in POV, MEGAPOV, Lightflow, BMRT (all in seperate windows).
Exports in several formats (including DXF).

See: http://www.geocities.com/hamapatch/program/index.html

(and on my system so far it seems very stable)

Have fun!