Sorry, I don't have one but your question did raise some thoughts. Will your son (or you) need to rely on the GPS for wilderness route-finding or other survival situations? I usually carry two GPS devices when out and about; one is a Personal Locator Beacon which sends GPS coordinates when activated in an emergency, and for regular use a hand-held Magellan with color viewer. Advantages of the full-size GPS are related to size, of course; larger display can be critical when making the choice between this creek or that canyon. Larger housing accomodates bigger receiving antenna for faster and more continuous aquisition, plus bigger and hopefully more accurate altimeter/barometer and compass sensors. It seems the wrist GPS units are best suited to running and training when linked with heart monitors and smart phones with fittness apps.