Individual files sure but apart from sending one file there are many more transfer jobs. People can buy 4TB HDDs from their office supplies store, and the fastest way to transfer data remains putting it in the mail, not because of bandwidth but lack of services. Cloud backup is much cheaper than buying a tape array and administrator, but at present that is all you can do with it -- backup. You should easily be able to have TB of personal data in the cloud and send any file/directory, without worrying about how big it is.

Resumable transfers seem to fail a lot with http. Block level differencing (like dedup) can also make things a lot faster.