When you are packing a bunch of spinning blade(mowing grass), or 50" sharp knife(plowing snow) and they say @9ft radiusI just like the idea of GPS vs. a dead-reckoning type system for tracking purposes.
accuracy you kinda lose interest. What I want to test this winter for localization is http://www.havahartwireless.com/shop/wireless-dog-fence/custom-shape-pet-fence
Tommy