I use keepassx as well for cross-platform compatibility and also have it synced between my devices on a personal cloud stored on my NAS.
Generally speaking it seems all the above answers are based on a variety of password manager(s) synced using a variety of ways (dropbox, drive, etc...)
The major flaws I see with this method are :
- if another entity has a copy of your password database (e.g. online-third-party sync services)
- if you become amnesic and forget your main password or passphrase (e.g. after an accident)
- if you mess up in your sync system and erasing it on one device erases all other copies you have on your other devices. Although i admit the chance of that ever happening could be close to nothing, I tend to think having a synced password database does not dispense you from backing it up once a year or so.
The real danger to me is the loss of your main key through no fault of your own (amnesia). Having thought a bit over it I have considered a viable fail-safe would be opening a safe vault to my name and storing a written copy in there. Eventually after amnesia you could discover a paper trail back to the vault and recover your precious data. Kinda james-bondish a method and with a price tag on it so this is only thoughts for now