Given the way a GPS works, I dont see this being feasible in the back country, where it would do the most good. I dont see an antenna that close to the ground, with your whole body above it, working that well. And, you would have to change the batteries in your shoes. Hell, I dont even TIE mine sometimes, when I'm feeling lazy!
I have been using a GPS for quite some time now and, even with a top of the line one, I get crappy reception with dense overhead cover. Spending $300+ on something that, in all likelihood, wouldnt work as advertised when the chips are down, seems unwise to me.
But, maybe the deisgn is better than I think. Maybe the price justifies it. Maybe it woulod work better than a PLB. Maybe its an item you will forget to change the battery in, and it will let you down when you need it.
Gimmicky, probably be all the rage in L.A. & NYC before the year is out. And, if you cannot navigate using city street signs, maybe you shouldnt go outside <img src="/images/graemlins/blush.gif" alt="" />