SM hired a guy like stefan and his co-workers to re-do the poser render engine, but they hired a guy like bill to do some other stuff with the library, scripts and the shaders AFAIK.  however, they were all agreed that, for the <10% of poser users who know how to do shadows and GI, FFRender needed more work.  in re: some renderers being too slow, that's true, hence for commercial movies they use alotta tricks, shortcuts and hundreds of gofers.  if ya hire 200 d00dz to do some renders and half of 'em are goof-offs, it's still ~100X faster than doing it yerself IMVHO.