Can also confirm that Poser 8 does not touch other versions of Poser you might have on your system.

As stewer says... just link to your other runtimes. Sooo easy in Poser 8. I currently have my (now older) Poser pro and an even older Poser 5 runtimes connected to Poser 8.

The new library features in Poser 8 are very good... I am finding that switching backwards and forewards between runtimes is virtually instantaneous.

"You don't have to be mad to use Poser... but it helps"