Since noticing this thread, I've looked into it. My wife and I carry a PLB when we're backpacking. The rule with that device is that "If you push the button, a helicopter will come. If it's not a life threatening emergency, you're going to have a very large S&R bill." I've seen the helicopter come.
The other devices are just something I don't want to get involved with. If I ever needed to have anything like that, I'd be out of cell service, so that'd mean a satellite rig. That's just too much money and bother, plus the chance of false alarms. Living has risks no matter what. I just had a very good friend and riding buddy die in bed at 60 y.o, really strong guy in fabulous physical condition, had spent the day backcountry skiing. I've made it this far and think I'll just keep going.
I'm a road rider though. If I rode BC trails, I might have a different opinion - or maybe not. I think I'd just carry the PLB, figuring that if I needed help, it'd be because the bike was broken and I couldn't walk. That's life-threatening in the back country. If I crashed but didn't really need help, letting my wife know I had a problem might not be the best approach. If I could walk out, I could always come back for the bike later, no need for S&R.
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