Couple of years ago, our troop/crew did a canoe trip at Northern Tier (Atikoken). The guide had a sat phone in case of dire emergencies. I carried a SPOT to mark our locations (mainly camp locations) and as a back-up in case something happened to the phone. One of our adult leaders had a prior heart attack several years prior. Having the 'OK' messages every night help calm his wife back home. I carried the 1st generation SPOT. You could accidentally send off help or 911 signals. As a result of an incident where this happened on another canoe trip, I had to carry the SPOT with the batteries out of the device. I doubt that would apply to the newer version of the SPOT as the help and SOS (not every country uses 911, some use 111) has a protective covering to prevent accidental activations.
Note: I used the new version SPOT in NZ where I had to activate the SOS signal (came upon a bad motorcycle collision in a remote section of highway). Worked great, got help there in about 45 minutes, but it scared some folks back home for a while. The SPOT operator questioned the two people on our emergency list about our descriptions, medical conditions, etc. They were impressed with their professionalism. The daughter of the couple we were traveling with told her parents that they needed to get a SPOT, too. When the emergency responders confirmed that we had activated the SPOT for the wreck and that we were okay, they called back our emergency contact people and let them know that we were okay.