We were talking about it at work (I work for a copy the develops EMR software) and it sounds good but what happens if the information got into the wrong hands. There is no such thing an totally secure systems. If someone wanted the information there are too many ways to get in.
I would be ok with it if it was only my emergancy medical information. Blood type, allergies, serious medical condition, emergancy contact, name, age, etc.
The whole tracking thing is ok, but what if someone hacked into the system. They could use that to figure out where you were. Takes stacking to a whole new level.