Per Old Salt's request:

"More I read about the SPOT type devices, the more I think they're more for the loved ones peace of mind than the person they're worried about?

Since you have to be able/conscious to send message with any of these items, I'm thinking IF I ever want something, I'd go the rental SAT phone route."

I agree the main motivation for me having a Spot is for my wife's peace of mind.  She worries so the no news is good news and trekking without knowing anything has become unacceptable.

"Took a SPOT on my 2013 solo as at the request/demand of my wife. Found out that only a third of what I thought were successful "all OK" transmissions ever went through. Told folks on my list to watch for any "send help" messages but warned that if no all OK messages were received it did not mean there was a problem. Could be operator error, device issues..."

I have read some reports here and other boards of a Spot not sending a message.  I discovered that if you don't leave it on long enough, it indeed won't send the message.  The blinking green led with the "envelope" icon on my gen 2 does NOT mean the message has been sent, but that is sending.  It seems some users think blinking green means it has been sent. Not so.  I now always leave it on - usually sitting on a rock around the campfire ring while I'm setting up - till it auto-offs - usually about an hour.  Since starting that practice, no failures.

As far as responses, I program one of the message buttons (there are three on the Gen 2 - Check In/OK; Custom Message; and Help/Spot Assist - which are all the same - you can write a message and edit a recipient list.  I program the Help/Spot Assist with a - "I'm OK for now but can't move" message - like broken leg, lost canoe, or other injury or issue that forces me to stay where I am - and limit to my sons to make intelligent choices:  come get me, look for assistance to get me, or call for emergency services if that is only option.  Helps they will know where I am - middle of no where or a half mile from an EP.
I have also programmed the "custom message" for a unscheduled pick up/shuttle - incase something is wrong but I can get to and EP or other point where I'm close to a vehicular access.  Again someone may be able to call an outfitter or other or do it themselves and the coordinates should clearly show where.  Food poisoning, injury allowing movement, lost paddle or canoe but can hike to ep - who knows - just seems like a good option to SOS and waiting for Sergeant Preston and the RCMP to show up.  (Kidding - I'm sure the Sergeant and King have retired by now.)

Granted an In Reach or Spot Connect or sat phone - all would make custom messaging simpler.  I won't take one of those because I'm an addict and would use it too much - especially for business.  Others may more easily be ably to control that addiction.  But I don't see how a phone or other texting device is any more reliable or usable if you are hurt or unconscious.

I suppose the ultimate safety and peace of mind solution is to carry both a PLB - on your person - and a sat phone - and check in every night.  Would be nice to have a tracking device as well because knowing where you were last would seem to be a huge help.

I won't deny that the PLBs are more powerful as many claim, but they don't reassure my wife and the Spot (and I suspect In-reach) are more than powerful enough.  I drive 4 and 6 cylinder cars which are powerful enough and I don't need an eight cylinder Hummer, which are indeed more powerful.

Any report or recounting on the boards of actual 911 use of the Spot seem to suggest it works well.  The older couple on their last trip and one drowning below Basswood falls I think this year or last; the Rebecca Falls incident where a dad with kids used it for another party (and freaked the mother at home till the Rangers let then use a sat phone a few hours after the 911); and two other incidents reported here.

I remain reassured it provides my wife peace of mind, some family and friends entertainment following my progress, and would provide me emergency assistance if I'm in trouble.  Obviously any device might not help much for a stroke or debilitating heart attack but my biggest fear has always been an ankle or leg or something that prevents me from walking - those typical Q portages being the issue.

I am changing my ways - adding tracking and keeping it on my person rather than in my pack.  That way if it does stop working or I'm injured or in the water without my packs, I have some options.  Also, presumably if I loose it, the tracking feature will help me get close to it if I go to retrieve it.

I have been preparing a caution note for a first time user - a leader with Scouts.  That includes strongly cautioning the recipient - parents or guardians above all -  that most likely no message means you left it in the car, you lost it, you didn't leave it on long enough, the batteries died, or you forgot to send a message all together.  Second, a 911 could easily mean you are summoning help for someone else - especially since these leaders and Scouts are probably some of the most responsible and best prepared of people in the wilderness, and are extremely risk averse.  I'm interested to learn of the troop will ever do it again after this try.

That's my story and I'm sticking to it.  YMMV.