I have a TK102B on mine and I hope I never need to use it

. I always put a fresh battery in before my first flight of the day and call it before I take off to make sure it txts me back with its current location.
To me it is better to have it than not having it. The only down side for me with the TK102B is that it weighs 55g and that takes my total Phantom weight to 1360g which is a bit over the 1350g specified max take off weight (less than 1% over so not too worried).
I will use this until I can find something better and lighter.