A blogger I read was in an accident with a car. (you can read about it if you click HERE),
He was wearing a Road ID. The EMTs had no idea what it was. I am not surprised. I was a volunteer firefighter for 7 years. I went through hundreds of hours of training and Road Id was never mentioned. Road ID advertises to cyclists in cycling specific media. You see Bob Roll advertising Road ID on TDF coverage that only cyclists watch but you don't see it during football games that everyone watches. That is the problem. An ID tag marketed to cyclists does not serve its primary purpose - letting non-cyclists know who you are.
I use a dog tag. Everyone in this country knows what a dog tag is. Every dog owner, war movie watcher, everyone who watches the news. Basically every emergency responder.When you are unconscious and unresponsive, your neck and chest get a lot of attention from medical personnel. They check airways, perform CPR. In those instances, a dog tag worn around the neck will be noticed where a bracelet on the wrist may not.
My dog tag has my name, address, phone number and blood type. If I had a particular medical concern or allergy it would be there. Good information in a place easy to find.
That's why I have a dog tag instead of Road ID.