I have limited experience with the Naza systems - flown other people's rigs. From what I understand after talking with experienced users, most Naza fly-aways are due to the Naza having the wrong home position recorded in the system.
For example, Joe Newbie, a guy that is new to the hobby and is excited about his brand new toy, takes his Naza based multi for a flight in the front yard. He does everything right the first time and lets the GPS get a good lock and record the home position there in his front yard. Then he takes off and flies around for a bit to the amazement of his neighbors. Joe decides that he is ready to brave the local flying field. He can't wait to fly around this open field and let this bird really stretch its legs. In the rush to get in the air, he forgets to let the flight controller record a new home position. He takes off and flies around a bit. He gets a bit too far out and decides to try that fancy RTH feature. He flips the switch and off it goes, headed towards the last home position - his front yard. Oops. But surely it wasn't Joe's fault. Must be that faulty flight controller (sarcasm).
That's just once scenario. There are certainly plenty of examples where a
DJI rig crashed because of a faulty DJI flight controller / firmware. But the GPS function on DJI's systems is certainly impressive.
All that being said, I fly Hoverfly because I feel like I get better video footage when I fly in manual mode. And Hoverfly flies really well in manual mode. There have been a few occasions where I wish I had GPS functionality, but I've gotten by fine without it. I do look forward to Hoverfly improving their GPS system.
