I don't know how experienced you are in these areas (OP) but I will give you my impressions as a newer and less experienced user.  I really dislike c4d.  

True it does render a lot faster than Poser but I have also had it crash far more than Poser.  Using C4d 10.5 Interposer Pro and PP2012

Once you get through the vast learning curve there are many things you can do to speed up your process with Poser figures.  There is a way to cut down on material maps so that you are only loading them one time and etc etc.  But those things take time to learn and patience to master.

Someone suggested Carrara as an alternative.  IMO that route isn't a great solution either.  I do love the speed of Carraras renders BUT I think the quality is lacking.  I see far more depth and realism in Poser renders and I don't know if that is due to lighting abilities or render quality.  I just know that's what I see.  Now I have the old express version of Carrara but I couldn't bring myself to spend any real money on Daz software when they are so notorious for not supporting their software and massive delays to bug fixes.

I'd say if you play to really really learn C4d and get use out of ALL of its features, it is probably worth it.  But if you are only getting it for rendering than it is a HUGE pricetag for a very limited return.   

I don't know anything about Lux Renderer.  I may look into that myself.

oh and before anyone flames my post here, please remember that I am speaking from an inexperienced stand point and I just wanted to give input from this stage in the process.

I am:  aka Velocity3d