In fact, Poser's smoothing IS subdivision, its just a bit more subtle one. Not Catmull-Clark. Actually, Poser's subdivision works great on many, many models which are low-poly and would look very strange in Catmull-Clark. 

Here is the P2 figure in closeup, with an Catmull-Clark subdivided figure next to her. Please keep in mind that the P2 woman wasn't built for CC subdivision, so the effect would even be stronger when it comes to Genesis.

Even in the smoother upper body parts, there are already differences. CC handles some areas better. Now imagine a knee or an ellbow, the effect is much stronger here.

Genesis for D|S won't need quite as many polys as a Genesis for Poser would. 

In addition to that - an smoothing angle of 120°makes hard edges difficult. Maybe not so much a problem when using it with humans, but with other models, this will be a problem IMHO. It is already visible in the face of your rendered woman, the smoothing is too strong in the eyes and around the nose, IMHO.

And even in your images, the smoothing isn't strong enough for the heel, which is still to edgy.

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