You know, I've had the program since it came out, and over the last few days is when I finally pushed it fairly hard: six Daz Gen 4 characters at once, plus clothing, plus 2 additional figures per character, plus hair (prop and figure) in an interior scene with mirrors and windows (so reflection and transparency) plus point lights plus shadows, plus shaders on some of the characters that included reflection, plus raytrace bouncing and (for giggles) one or two test renders using IDL.  The pz3 file pushed 500 MB because I didn't optimize any of the characters (removing morphs I didn't need, and combining others) or textures just because I wanted to push the program.

Aside from those few pixel render artifacts around the edge of some of the images, smooth as silk.  Multiple times I had to stop a render to fix or adjust something and the program was more responsive at stopping than previous versions of Poser.  Eventually I was confident enough that, when I wanted to make multiple images with the same basic setup (characters moving into a different position, for instance), I made a change and didn't bother to save a new file because I knew it would render and not crash.

The only crash I did have, in these several days, was likely due to an outside program that made a grab for a lot of memory at the same time Poser did and caused a conflict.

So, aside from that minor render issue, I am entirely satisfied that the program did what I asked it to do.