With Memrey we offer our users 256 bit AES encryption. If a user encrypts their notepad not even we can decrypt the users data.
Also we plan to integrate PDF backups emailed to you on a monthly basis. Right now you can download a PDF backup of any notepad, but automatically emailing it every month would be a nice way of having it be worry free.
If you get a chance I would be curious to know if you think Memrey would solve your issues? It is one of the most advanced notebook products on the market.