So I finally broke down and bought a SPOT Personal Tracker. A new smaller model came out, so I got an older one for about 50 bucks after rebate. You do have to buy the service, which is a bit over 100$/year. I bought the older model because it was cheaper, but also because its operating temperature range is -45C/85C, as opposed to -30C/60C for the newer model. My next race is going to be cold, so I might as well be ready for it.
I tried the unit and it seems to work as advertized although one must understand that there are limitations. Transmitting a message to outer space with a unit the size of a potatoe using 2 AA batteries as an energy source is an amazing feat of technology. And SPOT can broadcast your location every 10 minutes for up to 14 days on one set of batteries. What this means is that the SPOT unit has to be face up when transmitting a message. I tried transmitting while holding the unit in my hand vertically during a run, and the message did not transmit. If I held the unit logo-up for a little while, the message got sent, as long as there was a decent view of the sky.
The unit is not a replacement for a Garmin 305, as far as tracking your run. But if you find yourself in trouble in the bush, your 305 (or any regular GPS) will only be able to show you where you are. The SPOT unit will let others know you are in trouble, or even just keep track of how you are progressing on that 8 hour long run. With the training that is coming over the next few months, I will feel better carying it.