You will not have to make data calls, just start your app and go. Probably a long while. It is like the old joke about the difference between a computer salesman and the used car salesman. And I do this for a living. Too many marketing people are making technical presentations and too many technical people don't understand the world we customers live in.
Nothing ever seems directly comparable to something else.
THE GOOD NEWS IS you can ignore anything that isn't shipping today because it will almost certainly be different by the time it does ship. Things are changing that rapidly. By the time Sprint actually begins offering its 3G service the world will doubtless have changed a couple of times. But progress is being made, and we can look forward to easier and faster communication in the future, pretty much regardless of how the game plays out.