As I understand it, DSON is the file format used by DSF (and later DUF, for user files) - so since the Genesis DSF files hold everything except textures, which are linked jpgs and so on in the usual manner, a DSON importer for Poser would be stand-alone. Of course it wouldn't resolve all of the issues (SubD vs Polygon Smoothing) but to the extent that those can be worked around or resolved it would make native content available in Poser 9+. (I don't know if a Python script in Poser can call additional libraries, since I assume there's no built-in JSON reader and writing one from scratch would be an extra level of pain.)