I am an amateur photographer, who happens to use Aperture 3 to manage my photos and my photography workflow. I have a decent archive with 12000+ referenced files scattered around a few disks, and I am happy with how things are organized.
The software was finally working for me instead of the other way around, until one day I modified my images outside Aperture. Then I suffered from the problem where Aperture thinks I need to import thousands of images that I had already imported in Aperture, organized into projects, folders and albums, added metadata and image processed.
Google revealed tons of people reporting the same fault, but no prompt solution. Still, the information in these posts gave me ideas to device a workaround. I decided to share it so it may help another soul.