I get it. It has taken me countless Blender YouTube tutorials to understand the Cycles node structure and arrangements so that I may apply it to Poser. The PhysicalSurface node is just a better replacement for the PoserSurface node, except it is simplified and better suited to handle both Firefly and Superfly render engines. You would be better off using the PhysicalSurface root for everything; however, there is no convenient way to convert them automatically from the PoserSurface node. Honestly, the original PoserSurface node has outlived its purpose; it is time for individuals to gravitate to the PhysicalSurface node, which is better suited for physically based rendering.

Before I post a mini-tutorial on Cycles AO, I am running some tests with the PhysicalSurface and Cycles Ambient Occlusion nodes to verify their functionality in Superfly. This puzzled me for some time, but I think I am having some success with the outcomes. I'll be posting in a few.