As I said, syncthing seems to loose data over time, which would totally defeat the point of using it for backups. But something similar would definitely rock!
Having your own backups encrypted and saved in different places means that nobody would be able to steal your data, even though you have it stored over different random places over the internet.

A servomotor is the kind of motor you find in these radio commanded cars for kids. Typical electric motor, nothing special about it. You put a switch controlled by the raspi, and switch it on to slap.