So far, I couldn't find any non-functional parts in Poser 5/OS X, but two things that work better than in the Windows version: 1. The Poser window doesn't get obstructed when you render something and switch to other Windows. 2. all keyboard shortcuts are available with the parm dial palette as the active window. I suppose both of these features come for free with OS X - OS X is automatically buffering every windows' content and OS X is defining keyboard shortcuts and menus application-wide and not per-window like Windows usually does.