The SPOTs are used a lot for endurance/adventure races. Seems like they track fine. Main complaint I've seen is that folks just aren't sure if or when a message goes thru. Not much to go on with the display of the SPOT unit itself. There are some limitations with the service that only allow so many messages to be sent within a time frame and they are only sent every so often. So, the things people question are: can messages just disappear from the queue, or if they do go, how long does it take until it transmits?

You may want to wait about a month and check out one of the DeLorme PN-60w units. They'll be a set, a PN unit and a SPOT unit, linked wirelessly. You use the PN unit to enter your messages. I would hope that with the interface on the PN that it would show you what has been sent, is waiting, etc...

Here's a link:

http://www.delorme.com//about/pressreleases/TevaMountainGames.htm