> It's more data, but that's rarely an issue these days.

I do think it's a bit annoying that a program gets updated, and you have to download the whole 130 gb again.

But especially how quickly and easily you can compress two almost-identical files, I think your approach has a lot going for it. It may even be possible to get clever and send over just a hash of the original file, and a version of the new file which has been compressed with the original file as prefix (but without the actual compressed data for that).