I did a variation on the rule which avoids messing with any photos that I've edited - it will keep the RAW photos if they've been edited. All non-edited RAWs are deleted. This made sense for me, since if I've manually edited a photo, I probably want the highest quality RAW source to remain.
How to clean up the ginormous RAW files from Photos.app by exporting, deleting, then re-importing.
Notes:
1. This example made use of the fact that only one of my cameras was shooting RAW. You may need a different rule-set!
2. I've never shot in RAW only mode - if you have, these rules won't work for you.
Do a Time Machine backup first.
Make a New Smart Album in Photos.app
This will get all of the photos taken with my new camera (Sony A6000) which include JPEGs as well as RAW+JPEGs but will skip any you that I edited inside Photos.app, and will skip all of my iPhone photos which are never RAW.
Export Unmodified to a new folder:
Options:
Default options are good, putting all photos in single folder.
Export, then Sort by Kind in the Finder
You will see JPG as well as RAW files (for my Sony A6000, these are .ARWs - not necessarily for all photos, but only for the ones shot in RAW+JPEG )
Wait until it's done (there is no progress bar…)
In the Finder, Manually Separate the RAW and JPEG files to new folders.
In Photos.app, delete the selected photos.
Then go to the Recently Deleted album and Delete All
Note: I didn't see my drive space free up instantly - you may want to quit Photos.app at this point to let it clean up?
Go back to Albums / All Photos:
File / Import…
Select the JPEGs only.
Import all new files