Maybe it would be helpful to point out that we are talking about two separate purposes for ID. One is so those who can help in an emergency get notified. The other is to provide satisfactory ID to a person like a law enforcement officer when required to do so.

In that vein, putting contact information in my cell phone is one thing I do. But, since that doesn't satisfy all requirements I also wear dog tags and carry picture ID. If it isn't attached to your body don't count on anyone ever seeing it.

Check your state laws to see what is required for positive ID during a law enforcement contact. It varies between states. Then decide whether being prepared for a quick ID and you are on your way, or not having required ID and being held until you can be positively identified is the way to go. Personal choice.