Ok, so I have a contact sheet of "RAW+JPEG" images open, I select my favorites and give them a color to remind me that I like them (in this case purple). Of the RAW+JPEG combo I'll only take the RAW image into Photoshop for editing, after the editing the RAW image I save it as a JPEG with the same filename and overwrite the JPEG associated with that RAW+JPEG combo.
The problem...
Once I return to the PM contact sheet the color (purple) that I tagged the RAW+JPEG combo with has been removed. I still like it just as much as I did before the edit and I would love for it to continue to stay tagged with the color purple since hunting it back down and re-tagging it with a color takes a lot of time on those BIG contact sheets.
What can I do about this?
First you need to turn on a preference to allow your tag/color class to be preserved inside IPTC/XMP data. Open up the Preferences dialog. Click on the "Files" tab. Near the bottom is a popup menu titled "Save tag and color class in IPTC/XMP:". Click on it and choose either "For all photos" or "For RAW photos only". I use For all photos since I want my re-saved JPEGs to retain their settings, though you may want to do this on RAW photos only since you are replacing your JPEGs. Next click on the "IPTC/XMP" tab and make sure that you are allowing your photos to be captioned. Find the title "For TIFF-based RAW photos:" and look at the two checkboxes under it. By checking either (or both) checkboxes you enable Photo Mechanic to insert IPTC or XMP data into your RAW files. If you really don't want to insert data into your RAW files, you can keep both checkboxes unchecked, but you need to change the popup menu that appears below them to read "Always create and/or update XMP sidecar file with IPTC4XMP". This will limit the functionality to working only with XMP sidecar savvy applications like Photoshop.
Then you need to get this data updated in your "old" files. Click OK on the Preferences dialog. You should be back in your Contact Sheet. We need to get your edits reapplied into your IPTC data. Choose "Select Tagged" from the Edit menu. Then tag the selection (we're just setting the tag to its current value) by choosing "Tag Photos" from the Image menu. Next we need to update the untagged photos. Choose "Select Others" from the Edit menu. Untag the photos by choosing "Untag Photos" from the Image menu.
Now all of your files have their color class and tag settings saved inside their IPTC/XMP data. If you open one of your RAW files in ACR and then save it as a JPEG, Photoshop will preserve the IPTC and/or XMP data in the saved JPEG.
Now that you have this functionality enabled, normal editing of color class and or tagging will take care of preserving your image preferences across edits. You won't need to do the tag/untag work anymore.
HTH,
-Kirk