The trick with SD cards is to not buy the cheap ones, they are horribly fragile (similarly faulty cheap usb sticks are more and more common, sadly). I've been using a 512Gb Sandisk Ultra microSDXC for 2 years, and it's still rocking. It would not be a problem if it was to fail, anyway : I have several other backup storages, and I update that one daily, so I'll know immediately when it fails, it's not like I'll realize it the day I'll need it. On the plus side, it's small enough to fit in a small 3d printed object, so that I can both keep it on myself and keep it hidden, just in case (it's fully encrypted anyway, but still, better safe than sorry).