Poser's method of polygon smoothing is very specific to REYES style renderers; you can take advantage of it, but it requires specific modeling techniques.  It does not behave at all like Catmull-Clark subdivision, and has both advantages and disadvantages.
http://en.wikipedia.org/wiki/Reyes_rendering
http://en.wikipedia.org/wiki/Catmull-clark_subdivision

I think most people who model low-poly Poser content basically try to avoid using it at all (by breaking all edges everywhere, like Stonemason does) or turning off the Smooth Polygons property for the imported model.  For high-poly content it is much less of an issue, and models tend to behave in a way that appears similar under both methods - although at a low level some very different things are going on, the rendered result looks much the same.

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