The main thing i do is use Poser to set up scenes to be rendered by Vue Infinite; so the main concern is that PoserPro is recognized by Vue Infinite.  Since i have several older versions of Poser installed, I don't know what would happen if I got rid of all but Poserpro.

The main reason I am thinking of dropping the older versions does have to do with python scripts.  I might have one installed on another version, say Poser 7; and forget that i never installed it in Poserpro.  Then I pull out my hair looking for it in the wrong place. 

Disk space is not an issue.  I'll probably just keep the others just in case, and just treat the Poserpro install as the only one I actually use.