Hi Jimmy,
I bought one for George for Christmas right after I had my accident. We haven't had a chance to take it out on the trail yet (yes I gave it to him early, darn now I'll have to buy him something else ) however we have a friend that has one and he accidently hit the 911 buttom and lets just say it works really well.
I've always been afraid of having no cell service and needing help so I feel more comfortable having one with us. From what I was told the signal works better if you use the mounting hard ware but you can carry it on your belt as well.
Hope this helps, I'll let you know how it does when we take it out. IMO its a good idea to play it safe.
Cinda