I bet it won't be the Watchtower Society that will be faulting these things. What they will do is abuse them. People will sign out one when in field circus, and they will be expected to take the most direct route to the territory possible. That way, they will be able to enforce the Screech Arrangement where people are supposed to throw all safety to the wind and max out their productivity. They will know if you are only going 145 MPH when you are supposed to be doing 160. They will know if you are taking too long at one street (and you had better have a damn good reason, like a call that was long winded). They will be able to know if you are on a break (hence, stealing). If you park the car and go on a break by walking, you had better have placed tons of litter-ature along the way.
Not only that, but having a GPS system will help with finding those elusive streets. I have had a dozen or so times where I was working with a group who couldn't find a street that I knew where it was. I shut up about it to see how long it would take them to find it. A GPS device would cut such wild goose chases short, since they would have it come up in the monitor. It would then do me no good to keep quiet.
And, those out of territory calls would be that much easier. No longer would they have to hunt for the street. It would be right there on the screen. No more hunting for gas stations, either (and you had better use the closest one, and take the most direct route possible regardless of price, because the hounder-hounder is going to be able to upload the data and hound you if you don't).