I wonder how performant, mature, and reliable this is.
Mature: Well, it's been running nightly for years for me, and has saved the day on a few occasions when I've had to restore stuff from the vault.
Reliable: The only data I've lost was when a vault disk actually died, and I hadn't replicated it because, well, I was happier losing some history sometimes rather than buying more disk for that use case. However, when I get archive mode in production, I'm going to build a better vault replication solution than rsync!