The joy (for me) of a full FTM backup of my Ancestry data is that it includes all the images, photographs, etc. that I have added to various people in my tree. Ayes, aGEDOM file preserves the letters and numbers but not the gifs, jpegs, tiffs and other things beyond my pay grade.
As I hope I said, I'm not too bothered about the application software because MacKiev were there when needed them.
My whole system backs up every hour to an Apple "Time Capsule". It's in the house I know, but if that burnt down, frankly my tree is unlikely to be a priority for some time!!