OK - I'm predominately an Aperture user with a ~140GB library on my MacbookPro. Don't really use iPhoto at all - but don't iPhoto and Aperture share a library now? I think I understand that when I migrate/try the new Photos app, it will create it's own library file, but it will largely just be a set of pointers (my word) to my old library so that I don't lose any disk space. If that is correct (please please be correct), then I can't ever delete my Aperture or iPhoto library file(s) since the new app "points" to them to get the actual image data. Do any of these questions make sense? Any advice/explanation would be greatly appreciated.