I bought prop guards for my P3S shortly after I got it Christmas of 2015, and installed the brackets (these are the quick release type)-I have never used them, well that's not really correct, I did put them on for a short flight in my rather crowded back yard, and felt like they make my flyer look BIG, and LUMBERING, so I don't use them. but I still think they have a beneficial side effect-the brackets that the guards clip on also seem to have the added benefit of strengthening the area around the motors, saving the housing from the dreaded cracks around the motors. I do have the guards in my case and I'd throw them on if I felt it might save close-quarter brushes with walls or obstacles, and they are cheap enough so why not? A small investment, for a couple of reasons too, I think.