personal use
For personal use, as a backup repo I just use owncloud, and all my stuff is synched dropbox-style onto raspberry pi at home
The NSA would have a job getting through the backdoor because it kinda sticks
Private cloud firm Connected Data has birthed a business-class, private cloud/file sync 'n' share product based on its consumer Transporter product's base. Transporter is a mini-cooling tower desktop lookalike housing a hard drive with internet connectivity. Peer-to-peer networks of Transporters can share and synchronise …
Most modern cloud solutions should be using delta copying so its only transferring blocks of files that change, so assuming you not dropping GB of new data each day, updating large files is not a problem.
Own cloud / bit torrent sync is good if you need something simple for multiple locations, that said forget all the gui rubbish and just rock rsync or unison over ssh, job done :-p