That should have a firm hold with the helis tail.. there might be somthing wrong with your setup.. I flew a GF500 ALign heli with a GY410 for sometime.. and it was holding rocksolid... Never failed me in reverse inverted flights... just dont over do the heli.. Its kinda when you force the heli to move into a stall situation.. the gyro cannot help you out... even using a Spartan...