Hi,
I use 1TB micro-SDXC cards for offsite backups. In particular, I use a script that gtar-s (Apple's tar does not archive all files, but gtar does), bzip2-s the tarfile, encrypts with RSA, then splits the encrypted archive into 1GB subfiles, shasum-s all of the split files, and copies all of the split files and necessary scripts to the micro-SDXC card. I then send a micro-SDXC to the East Coast, one to the Gulf Coast, and one to the West Coast. There is a script that copies the split encrypted and compressed archive onto large HDDs at each site and checks the checksums to make certain that there were no transmission errors; and another script that will merge, decrypt, uncompress, and extract the tarfile, if needed.
The micro-SDXC-s are easy to tape to the inside of a Hallmark card and USPS mail to the three offsite locations.
I know that this is "ridiculous" ... but it works. And can be used to transfer other things, such as family photos that you don't want to loose or be stolen during transfer -- the encryption makes sure that even if the micro-SDXC card doesn't make it to the proper destination, you don't have to worry about anyone else having access to the archive on the card.
Solouki