We don't really have a timetable for P6, so I'd go for 5. It integrates most of the Pro Pack features, and unless there is some sort of liscencing fiasco, then the material shaders, dynamic hair and cloth, and few other goodies are here to stay. And ynsaen is quite right; we are at that stage (finally) where the likes of Traveller, Yamato, Syyd, and quite a few other of the original Poser guru's made their mark on P4. Enough people are finally starting to use the new features that the basic tricks are being found out, and the work arounds that either speed up the process or squeeze something new out of what's there.