I use Evernote for a lot of stuff, but I would be reluctant to use it for sensitive documents -- if my Evernote credentials were compromised for any reason, it could be a big problem.

Another way to do this is to use a cloud file service (like Google Drive) with files that are individually encrypted. If my Google credentials are compromised that would be Bad but if the critical documents were protected with strong encryption, that would make things much harder for the attacker.

With that said, I'm using a physical binder for most of those docs right now.