For me, Poser Pro was worth the sidegrade when it was on sale.  The background renderer is much faster.  I had a scene that took around 25 minutes to render in Poser 7, Poser Pro rendered it in 2 minutes.  I am not sure why there was that much of a speed up; but it did definately speed up!

As to the render nodes, good luck getting it to work.  I have yet to get it working, and no one knows why.