Yeah I sent Holger a U5 to test this past summer and it said it was fine under lighter loads. I probably had 300 flights with those motors this year. This is the first time I used the U5's since I had the incident where the one board caught on fire. It could have hurt the motor in the process. Nevertheless I think I'm going to replace all 8 with 4120's that way I have 2 identical copters.