I think PLB's are absolutely important pieces of gear. And while some think otherwise I decided to get a SPOT2 GPS messenger and here is my reasoning. YMMV.

Living in the desert there are a lot of areas in my primary endurance training were there is zero cell phone service. Even a basic breakdown on a state route would necessitate a very long walk out, let alone getting anything on trail. So the Help & OK functions are nice back ups for me.

As we all know, we can get behind schedule on the trail. And on great days where I maybe just dawdled too long instead of hitting my turnaround time, I keep going knowing I will be late. DW can either get a text update from me when I'm heading back (preset) or go to the SPOT shared page for a real time update of my position.

Heck even when I am with a group and we just decide to kick back and watch the sunset after a run or swim out there, its good positive reinforcement for my DW to know I am okay b/c I haven't called in when I said I would.
Don't just survive. Thrive.