I imagine that within the next ten years Poser 5 and 6 will be, either free, or so low cost all Poser 4 folks will abandon their old standby. :)

But right now there are still a lot of people using only Poser 4 so I try to make my sets compatible.

My version is 7 and I'll wait till they actually fix a few more things (And till I gather some cash as well) before I upgrade again.

I look at some of my first images from P4 and just shake my head.
Gosh how awful they look now but when I first started doing 3d art, they looked great.  Lol.
Thing sure change.

Let me introduce you to my multiple personalities. :)
     BluEcho...Faery_Light...Faery_Souls.