I also love the windsurfer on my P3P, I have over a million feet logged and it works fantastic, given it only cost $25. However the same windsurfer on my P4 doesn't work quite as good. Although I've demonstrated 15,000' with my P4 using windsurfer under ideal conditions, I constantly get sudden NO SIGNAL scenarios with no warning, meaning no control to the craft and no video. If the NO SIGNAL lasts more then 3 seconds RTH kicks in. I have NEVER had a NO SIGNAL scenario with my P3P, only weak signal, and I will start to lose video, but I've never lost control signal. My SOP with my P3P when I get weak signal is to ascend 100' to get my video signal back, which usually works. It's as though the control signal on the P3 is way stronger and more reliable than the video signal. I go 2mi with my P3P all the time (300' high at least) and rarely lose video, only rarely. But with my P4, I'm lucky to get 1.5mi, and many times I'll get dropouts at 3000-4000'. I'm disappointed in the step backward DJI has taken with the P4 Lightbridge, what they have coined "Enhanced Lightbridge". That's a joke, I would call it "Lightbridge-Lite". Otherwise I like my P4, I just wish it had the same signal integrity and distance as my P3P.