Thanks for your fast reply, but that seems a little insecure as well. The DMG's may have a highly encrypted password, but what if the "bad guys" just try to brute force the file where Espionage saves it's passwords in? So I don't think this is a good solution.
I know that keychain "only" does 3DES, but with a very long password, that doesn't really matter all that much. So it would be a welcome feature to add to this, so all protected folders can auto-mount on login.