I had a horrible experience the other day and lost all my character data. So what I have discovered is that you can back up and restore to a USB drive by going into your PS4 settings, application data, then looking in the FFXIV folder for your System and (most important) Character data files.

It didn't help me as I didn't have them backed up (I didn't even know about the location) but if you're transferring machines you should be able to move the data across. Just make sure you are logged in as the same PSN account so they don't get locked. If you have PS+ already then it works in exactly the same way; manually upload the files from the Settings area then download them again if the auto-backups miss them.

As I sit here remaking all of my action bars I agree with everything Niwashi said about giving us the option to upload character data to the server the same way we did the PS3 upgrades