@Mark, I really like the cloud variables, but they share info between all apps. I wish the variables could be instantiated with a username so that info in the cloud variables could be private.
For this reason, directly using the DB is better. Data security. The cloud variables are nice for personal apps or apps with limited distribution. Perhaps for a high score board or something. Like if I want to share a reminder app between me and my wife. On the other hand, to create a key for the real time data base, it is as simple as using a text log in to save user name. This allows users to store and recall information in private. This way Dad I will be stored under garage users email address which will be unique to the user