If anyone is interested in physical rendering, you don't need to be scared off by the high price of Maxwell. You can just get Indigo instead:

Indigo

It's free for commercial/non commercial work and has most of the features Maxwell does. It doesn't have a plugin for poser files though, so you'll have to manage with OBJ.

As for renderman, personally i'v never understood why they picked something like firefly for poser. Firefly, like most renderman compliant renderers, runs on the REYES architecture, the hallmarks of which are fast moblur and fast displacement. But barely anyone uses these features in poser artwork. They should have gone with a raytracer, which would have fit poser much better.