This is exactly what I do. I have an old headless Mac mini that has a 2 TB drive and syncs all photos via iCloud/Photos, then a time machine backup of that volu

This is exactly what I do. I have an old headless Mac mini that has a 2 TB drive and syncs all photos via iCloud/Photos, then a time machine backup of that volume. I can take a picture on any device, or copy in a picture or video, or import from my camera SD card on any device, and within a few minutes I have at least 2 backup copies available. I just wish Nikon, Canon, Sony, or anyone really would be able to integrate a DSLR/mirrorless camera into Dropbox or iCloud Photos so I could take out the manual import process :P