Find all "managed" photographs in Aperture 3
Click on Libray.Photos to show all your photos. (near top left of the Library inspector)
Click the filter icon to bring up Filter:Photos (near top right of browser)
Click 'Add Rule' and select 'File status'
Select 'Managed' as the criteria for 'File status'
If everything is referenced, you should have no images
Thanks! Much better than my current plans. Open package contents on the library, and browse through the Masters folder to look for managed files.