The one set to 200 is the occlusion cache, which doesn't get used at all in this case - that one's for AO only (and internally, Poser clamps it to a max of 100 anyway).

The deciding factor here is the second IC parameter. Basically, what these settings do is calculate a few, high quality shading samples (4096 paths per sample) and then generously interpolates between them. Because the indirect light in this scene is very smooth, this works beautifully.