I've had the spot 1 for a couple years and also 100% reliable. The OK's sometimes take a bit to get out, but they do. Clear view of the sky is needed.
The limitation I see for both devices is that neither has an automatic activation during an accident (like an ELT). Not sure the ELT gives you much guarantee of being recieved if remote either now, but keep in mind that if you are incapacitated in the "landing", no distress/911 signal will go out. I keep my spot right above my head in a RAM quick release, so if I do have to set down in a really rough environment, I'b grabbing it and putting it down my shirt.
Conceivably it will conintue to function in track mode (how I operate it while x-country), so the wife might figure out you haven't moved for a while, and haven't got an "OK" (my wife and I have an understood procedure), but if you have time-critical injuries, that's not the best option.
Nothings perfect. For 95%, the SPOT 1 has performed excellent and I do not fly (far) without it.
The public website for tracking is fun too (as you see on some folks signatures).
Some example tracks form flights - 1st is from the spot shared page coming back from Johnson Creek
Downloaded to Google Earth coming back from Douglas WY
