Yea, there are plenty of backup options out there. I never use them. I had a Nexto but found it simply too large to screw with, too heavy to carry around and the battery life sucked rocks. Took it on one trip to Disney. It made the rounds in the park one day and at the end of the day that half pound felt like a lead ingot. I sold it when I got home and bought a handful of SanDisk Extreme cards, pocketed the leftover cash and never looked back. Now I simply carry the extra SD cards. They are cheaper, smaller, lighter and take exactly zero time in the field. They solve three problems in the field at once. Full cards. Broken cards. Lost cards.
The backup devices don't guard against failed/lost cards while out shooting. If you drop one in the drink or one fails and it was your ONE card, time to go home. Since I carry cards instead of backup devices, I just pull another card out of the pack and continue shooting. (Yes, one of my cards is at the bottom of the Jungle Cruise at WDW under the bridge I was standing on when it fell through the crack of the planks.)