Why not use Amazon Import/Export instead of upload/download?
Working on Big Data, we routinely have to transfer terabytes in to the cloud and we would not use upload for anything that is over a terabyte. Amazon offers Import/Export service which allows you to send physical media (think cheap SATA drives) and for $80/disk they will import it for you and return the disk back to you. For large volumes of data it is the only way to go.