I always carry one when I go solo hiking. The one I take with me has a scan function that searches all of the channels for people talking. If you get into a jam, you can scan for others talking and then fix on that channel to communicate with them. You may have to determine which subchannel they are using, but it gives you options.

And like you said, if you left your predetermined channel with for family or friend whom you told "where you were going and when you would be back", that information could prove valuable to SAR.