Interesting idea. The whole dog-tag thing works well too. I could see the final product having the same pressed alloy aesthetic as the real thing, maybe with some nice machined surfaces for contrast.
The only problem (for a real world perspective that is) is the GPS patch is shielded by the LCD, plus the patch needs to be angled towards the sky in order to ‘see’ the satellites. This is especially important in a built-up environment (where the fear of an attack would probably be the greatest) because the building tend to restrict the line of sight to the sky to a small arc overhead. 