"No one listens for that signal until someone reads a formal climb plan somewhere and decides the climber is long overdue."
Hmm, that differs from the description I saw on the manufacturers website... of course they ARE trying to sell the things- The ones I saw were in the 600-700 dollar range and were actually satellite communications... When activated the claim was local authorities would be notified of the distress signal and its general location and then they could go out and track it down.....
Maybe we are talking two different things...