I am sure that the aperture community has dealt with this before.
Prior to purchasing aperture, I made sure that metadata like captions keywords, etc. could be written back out to the master file. This would allow one to not be held hostage to aperture. With various updates this ability has gone away. The statement from Apple less than a year ago, seems to indicate that aperture will not write metadata back out to the Masters.
By Design: Aperture won't export metadata with RAW masters
Unlike applications such as Photo Mechanic, Aperture does not write IPTC and keywords to the original RAW file. Instead, Aperture stores this information in its library and attaches it when exporting versions in JPEG, TIFF, PSD, or PNG format. If you export the RAW masters, none of your metadata changes will come along with them. Unlike the issues listed above, this feature is by design.
If your goal is to archive RAW files outside of Aperture with metadata attached, you'll need a workaround to this aspect of Aperture's metadata handling. Because Aperture is designed to read added metadata at time of import (despite the current issue described above), the best long term solution (after issues are resolved) will be to add your metadata in Photo Mechanic (or similar) prior to importing them to Aperture and then refrain for the most part from using Aperture's metadata tools. If you don't like that workaround, a secondary workaround is to export JPEG versions to be kept alongside the RAW masters. To save disk space, the JPEG copies could be a minimal size."
I am sure that many community members have encountered this problem. Specifically, I have many slides to scan, so the raw input file is a tiff. Aperture does not support writing metadata to tiffs. And to depend on aperture to write out metadata to any master file is probably setting yourself up for disappointment.
Can the community recommend a way around this?