What's different about the OBJ that Poser writes out?  For one thing, the geometry is cut apart at the borders of body parts.  Keep this in mind if you want to modify the OBJ later on, after you've rigged it.  If you import the Poser-written OBJ into your modeler again you'll see how this affects you.  Just using it inside of Poser you won't notice it because Poser quietly re-welds it back together again when it's loaded.

Why does Poser do this horrible stuff to your wonderful watertight model?  I have no earthly idea, I'm sure at one point there was a good reason but this is one of those mysterious things that will make your life very, very hard if you're trying to do fitting morphs for conformers in an external application.  Since the vertex order and vertex count is completely different between your original model and the Poser-written version, moving morphs in and out of Poser is frightfully weird.  People have written applications to make this less painful (D3D's Poser File Editor does this also, and there is Colorcurvature's morph loader script).

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