But wouldn't you agree that your brain + NoKey instead of a piece of paper as a backup would be more secure? And more convenient, as you don't have to type your passwords anymore.
I don't wanna push you, just wanna give you some things to think about. As long as you use strong and unique passwords everywhere you're good.
Also, it's not a big problem if one of your devices dies, as long as you paired enough devices you won't lose any passwords.