Your wrapper is only lacking one critical feature I'd love. I am currently using rsnapshot and while its big issue is lack of encryption, it is able to run scripts on remote hosts to pull backups from them. This is a big deal to me since I can then script things like MySQL/Postgres backups, etc. on my master server, rather than having to configure each host individually.
It's possible that this is a bad way to run things since my master server is then a SPoF. I do trust this server more since I monitor it much more closely, than I would a dozen random VPS's with a half-dozen different providers.