I think almost everyone concurs Poser 6 is the most bang for the buck. As to how things from earlier versions of Poser behave, you will find some things, props especially, that will render with black patches. This will occur in both Poser 5 and Poser 6. Once you purchase your new version, be sure that something has been tested in Poser 5 or Poser 6 before you buy it. Not everyone is supporting the newer versions, but there's plenty of compatible content out there.:)