Mark consider that you are the one who made the choice to stay with Aperture years after Apple publicly gave it the kiss of death. So you are at least partially responsible for any pain and suffering related to continued use or migration. 
If Aperture will open DNG files, why not use Adobe DNG Converter to migrate native raw files Aperture can't handle into raw DNG files it should handle?
I fully agree Photos is definitely not an Aperture replacement. It might be good for the casual shooter who mostly uses IOS cameras.
I have cancelled and deleted all my photo editing apps except those from Macphun (Luminar, Aurora, the CK apps) and Photo Mechanic. I use Photo Mechanic to do all the imports.
One of our photo clubs had a field trip with contest. Once I culled down to my candidates, the editing was very fast and all within Luminar. I won a first place. So I am a happy camper. 