My dad bought the new Garmin GPS tracking system and had it on his feist for the first time last weekend while we were hunting squirrels. Dog jumped a rabbit and took off. the unit kept up with him incredibly well. You know exactly where the dog is as long as he is within the 5 mile range of the radio signal between the collar and the handheld unit. My personal opinion is that would be the only downfall of the unit. It's alot easier to use and more accurate than any radio collar. The handheld unit is also used as a personal GPS so if you are inclined to carry a gps with you, you don't need 2. It will keep track of you and up to 10 dogs all at the same time. I don't have much experience with tracking collars, but of the 3 types I have used this is by far the most user friendly.