Make sure you take your phone OUT OF ITS PROTECTIVE CASE to fly the P3.  I suspect people that report overheating issues when using the GO app are leaving the phone in a bulky Otterbox or even a simple phone case when they fly. (Irixguy on YouTube clearly suffered an overheat crash on his 6+ in his GO App review)

For IOS devices (6, 6+), the aluminum back is also heat sink, if you wrap it with a case the heat can't dissipate. Also, try leaving a small gap between the device holder and the back of your phone when you clamp it into the controller.

  

i use lifeproof case with my iphone 6+ and never had any overheating issues, as long as it is not in direct sun light!! even if not using the app, if u leave phone in direct sun light, it will give u temp warning within couple mins.

Nice tip!  Thank you!