I think this is a good basic and relatively low-tech strategy.
Do you do versioning? As in what happens if your files are silently corrupted e.g. by accident or by malware? Rsync would overwrite your files, and you might even overwrite your off-site backup when you connect it.
My main reason for going beyond such a set-up though is that it takes time, effort and remembering to sync the off-site backup by taking it home, syncing and putting it back. And during that time all your data is in the same place. If something happens to your home during that time (break-in, flooding, fire...) you're out of luck. Unless your rsync'd drives are also encrypted and you just switch one of them with the off-site one for rotation.
Do you do versioning? As in what happens if your files are silently corrupted e.g. by accident or by malware? Rsync would overwrite your files, and you might even overwrite your off-site backup when you connect it.
My main reason for going beyond such a set-up though is that it takes time, effort and remembering to sync the off-site backup by taking it home, syncing and putting it back. And during that time all your data is in the same place. If something happens to your home during that time (break-in, flooding, fire...) you're out of luck. Unless your rsync'd drives are also encrypted and you just switch one of them with the off-site one for rotation.