We are talking here about Dropbox being simple to use for everyone and you start talking about keeping backups of keys. In safe deposit boxes, no less. Wow.
You don't need to worry about safe deposit boxes. Just don't be upset when you get a letter in the email from a law firm that's noticed some of the music in your dropbox has the same hashes as the music in someone else's dropbox.
The cloud is a scary place. Making it easy to use is not necessarily a good thing.
