I'm looking into getting a SPOT tracker. Does anyone have one of these and if so, what do you think of it? Are there other brands of tracking devices that I should look into?

Also, I was researching on the SPOT website and noticed that they have the "SPOT Satellite GPS Messenger" and the "SPOT Personal Tracker." From what I could tell, the SPOT Satellite GPS Messenger is the newer device and has a few more functions. The only thing I want the SPOT for is emergencies, not so that I can text friends/family and tell them that I'm okay. It seems like the SPOT Personal Tracker (which appears to be a little cheaper) will do the trick for me.

A non-pilot friend of mine also mentioned that the I-phone has a GPS tracking application. Would that work???

Thanks in advance for your feedback!