Just my two cent. I have worked with the free Poser to Luxrender plugin before and although it needs a bit more tweaking it can easily be tested to give you a feel of how Luxrender works. Reality, which I tried today is much simpler in use as it needs less tweaking, it already knows what is skin, cloth, etc, but I sadly already had issues that it did not understand all node information and the clothing textures came out dull. The metals and glass materials Reality come with are much superior to Poser versions and they do truly reflect lights, etc...Luxrender renders are more true to what we see around us and the lights Reality ships with are easy to use and achieve good natural looking renders. In my case I am sadly very limited as to the size of renders. Paolo suggests renders at 1200x700 which for me are too small, but the sizes I am used to render as in 3000 and up, hog my system and ended up crashing Poser and called for a reboot....

If natural is what you aiming for Reality will do it, but you might not be able to add much stuff to your scene or render big. It is all system dependant. A basic render in Lux took 52 minutes for me to find it OK (1000x1000). It thus also might depend upon how much time you are willing to give it....

RDNA has the official forum and many people have posted there. Maybe it is worth having a look?