Has anyone had hands on experience with this app and it's associated hardware? My friend has an autistic 11 year old son whose movements are becoming increasingly difficult to monitor. On paper this system would appear to be perfect for her needs. We live in a rural area close to mountains, rivers and fairly rough terrain and it's very easy for a child to get lost very quickly once they've absconded from a house. I would really appreciate any feedback anyone might have. Thanks.