I could be wrong, but I think it isn't either companies fault per se that it isn't compatible with Poser 5 yet. I think enough has changed between Poser 4 and Poser 5 that a new SDK would need to be released for E-On to write the importer. And Curious Labs at the moment is spending so much time fixing Poser 5 that they probably can't commit any resources to writing the SDK. Besides, wouldn't it be better in the long run to have the SDK written around a stable Poser 5?