This looks like a great tool. To answer your earlier question +Koushik Dutta
only the latest backup is really necessary, unless you need a redundancy for sync.
I would really like to keep certain apps synced between two devices - game saves, for instance. Or settings. Being able to play or configure an app on one device, install it on another, and have my progress or settings just automatically match that of the original device would be ideal. I don't know if that's the direction you are going or not.