Doesn’t DNG mean my backups will be huge?
If you save metadata back to a DNG, doesn’t it mean that every time a change is made the whole large file needs to be backed up?
Not really. It obviously makes no sense to keep backing up big DNG files after every change, but that’s a straw man argument against the format. Instead you simply backup the DNGs upon their creation, and routinely backup your catalogue. If you were to hit a catastrophe, you can reconstruct the exact state of your work by restoring these virgin DNGs and your catalogue. Sidecars don’t contain all your Lightroom work.
This is true if you have a backup system that will ignore all the dng (or existing files) and that only backs up the catalog and/or any new files. My backup system, and pretty well any other system that I’ve ever seen, backups all new and/or changed files. I wouldn’t want to do it any differently either because how can I possibly know algorithmically which changed files should be backed up and which shouldn’t. Therefore I long ago made the decision to stay away from dng and stick with cr2/xmp files. Of course I also backup my catalog regularly, but I don’t think that is a robust enough solution on its own either.
I do it simply by having a new drive which gets backed up, and an archive drive which mirrors my write-once backups.