I don't think that on-line sites are meant for 100's of GB of data. I think it is useful for the really important files or folders that may change frequently and need to be backed up.
To create a backup copy of pictures or other media, I think a local hard drive solution (using a 1.5 T drive) is the way to go. If you really are paranoid, you could store the drive+enclosure at another location or in a safety deposit box.
Sending 800GB of data over the internet doesn't make sense to me. Not only will it take months to get it there, if, heaven forbid you need to recover it, it will take weeks to get it back! And you'll blow your upload/download limit on your internet service and pay huge fees on top of it all.