Restic looked interesting - I would never have guessed it didn't support such a fundamental feature as compression?! So thanks for mentioning this and saving me from wasting my time.

Note: I'm not trying to be horrible or disrespectful to the Restic devs; it's just that backup without compression is a complete show-stopper, especially if you want to use cloud storage (where storage space, storage operation, and bandwidth all eat money).