I've been experimenting too .. the low res mesh does subdivide to the same poly count as the high res mesh.

UV Mapper Pro is definitely helpful for a go-between, from the original OBJ to your modeling app to Poser, to make sure that the vertices don't get reordered.  Another key is to probably use the ENTIRE OBJ file and not divide it into individual body parts.

I know it can be done, but there is a lot of back and forth between the apps, and passing through UV Mapper Pro to verify UV mapping and grouping.