You folks know you can get a low mileage discount without those stupid devices, right? I have one. I think car services report the miles so they would probably know if you were lying, but I am not so it makes no difference.
I was already getting a low mileage discount (under 7,500 miles), but got an additional discount with the Drive Safe and Save device (State Farm).
The only way my rate could go up (using the device) was if I was already getting the low mileage discount and the new Device showed I was actually driving more than what I was stating to get the low mileage discount. I only drive about 3K per year on my car. We put on about 15K on the wife's car.
I'm certainly not trying to talk anybody into using one of these devices, but am pleased with the $400 per year I'm saving. If that goes down substantially next policy period, then I'll just get rid of it. You can also just disconnect blue tooth for awhile if you have a certain trip that you don't want recorded. I've done this on vacation since I tend to drive over the speed limit on open interstates.