I flew a 5c in my back yard for a year, winds, trees, and the house created a lot of interesting experiences. After realizing that I had very poor GPS in the yard, flew the P3S on Atti for a battery full and realized how good the P3S is to fly. Took it to a field for a first real flight and realized how useful the 5C training was. If somehing goes wrong and you lose GPS you need to be able to fly in ATTi and the only way to do it is to fly (on a large field trying all the different orientations in flight) it and try to understand what the bird looks like (stick reversal can get to you).