"What happens if your password manager goes titsup (or the disk it's installed on)?"
Some of them store the details in cloud (useful for multi-device access, but arguably a bad idea for security), but this is a backup issue, not a Password Manager issue. At the end of the day you can't expect your password safe to sort out your backup processes.
"Also how easy is it to transition back off them?"
All the Password Managers I have used allow you to export the contents to text or XML. With many warnings that you are exposing your passwords, 'natch.