Well, I am worried about corruption. It's happened to me more than once, even with the latest version of Poser 11. (I don't user Poser 12 that much yet.) Seems to be more common with larger scenes. The last time, it was a scene with 10 figures, all dressed, posed, with hair, etc.

But I've never had trouble using PMD files, even though I have Use external binary unchecked. You don't even notice.