Hi Robert,
You are completely right about the benefits of real time information through radio, very useful when no mobile service is available. It is also an incredible training tool. I use it now since fall 2012 and it changes completely our ways to train our birds.
Just a little thing: not all existing systems are solely gsm based as you assume, some of them also offer real-time information through radio together with the phone feature.
About the phone network, a question: how does the map app work when there is no mobile service is available to load the map: is there a kind of memory to have the map available if no mobile service is available?
Thank you