Yes, I have experience with this technology: my young neighbor has one on his chocolate lab, Buddy. It's a thoroughly useless device, in my experience. Buddy gets out a lot, and since his GPS tag is is only link to his owner, it's hard to get him home. The owner never seems to have noticed Buddy's gone, so he's not using the map to locate the dog. Even when he's using it, the tech doesn't seem to be all that accurate, as he's sometimes a street over.
To find his owner, someone has to bring Buddy inside, post him to the neighborhood Internet forum and/or Lost Dogs on FB, wait for his owner to notice the post and call to arrange to come get him. A simple, cheap metal or plastic tag from the machine in the lobby of Walmart or Petsmart would have had Buddy home within minutes of finding him. Heck, even a registered microchip would work for me because I have a scanner.
Even if the tech allowed it to have its own cell phone connection that pinged the owner when the dog was on the move, I would not have my dog wear a device that would keep exposing the dog to constant cell phone radiation against its throat -- too many unknowns right now (and dogs concentrate exposure into smaller bodies):
Save your money. Microchip your dog and register it (cost: $15 at a Petco or feedstore vaccine clinic). Buy an ID tag (cost: $5 from a machine at Walmart). You'll be out around $20, and your dog will have connections to get back home that people who find dogs know how to use.