I got a SPOT for father's day. Love it. As long as you have a clear view of the sky, SPOT will get the message out. I set up to send text messages and email to my loved ones. They all like it. I just recently went on a solo trip where I ended up bushwhacking. I had the tracking mode enabled. When I got home I saw exactly where I was and I knew that if I had gotten into trouble the SAR folks would've found me very quickly - whether or not I was able to push the 911 button. My wife was watching my progress the whole time, even though she new nothing of the area.

It is true that canopy will block tracking and OK messages. I'm not sure about HELP. I'll have to check the manual again, but I believe that HELP and 911 messages will be sent whether or not SPOT is able to get a GPS fix - unlike Track and OK.

It is very easy on batteries. I'm waiting for it to use up the first set - hard for me to get used to the idea that 2 Lithium AA's can go that far.

The unit definitely works better if you mount it face up on the top of your pack - not hard to do.

I turn the unit off when switching from Track to OK - never had any problem with it that way. When sending an OK message the unit will blink both LEDs green if it got a GPS fix and sent a message - easy enough. I haven't tried the HELP feature yet - I'd have to turn off or warn the loved ones first so that they don't start calling.

I don't know if plunking down $100 bucks for the service will be the best deal long-term, but for this year it seems like a winner.