There's been render presets for the sketch renderer shared in a similar fashion. I would think it's generally safe to put files in the AppData/RenderPresets folder. Messing around in the main runtime prefs folder I'm not so sure about. I would say they're just reference files though, similar to how any library/textures/geometries file would work. I can understand your reservations. Some people don't like to mess with Poser files, some do. I would imagine that direct reps of Poser Software wouldn't ask you to do something that would be harmful.