Interesting, though I was hoping for a bit more focus on the validation part - unless I'm missing something, there's nothing protecting the actual SQL dumps against bitrot.

I had to design against that particular problem recently, ended up taking a pt-table-checksum at the time-of-dump and verifying newly restored backups against that to ensure the backup's integrity.

Unfortunately that requires halting replication temporarily, so I was hoping to hear of a more ingenious solution.