Here is my thought...
keep in mind using a Futaba 9202 on the raptor 60 is okay for hovering and slow FF...anything assoicated with 3D....will result a stripped gear just as you stated.
Please use something stronger than 92 oz inch of torque on the collective...something like Futaba 9252 would be a good source collective....but more than 92oz of torque would be better.
If i remember correctly that 9202 has about 63 oz inch of torque...not an ideal stick banging servo.
Unless the higher torque servo has a stronger gear material, it will not be less likely to strip under load. Given the same gear material the lower torque servo will actually be LESS likely to strip, unless the torque/load ratio is so bad that the servo arm actually gets pushed back, to its physical extreme.
I'm not denying that he would be better off using higher torque servos, but I don't think having one would have prevented the servo from stripping (again, unless it has stronger gears).
The heli made a twich in the up direction, and the heli started to do back flips.
If the servo gears stripped during flight, how was the servo arm able to apply the pressure required keep the cyclic in the aft position to do continuous flips?
I'm not sure why the heli started to do flips, but it sounds to me like the servo stripped when it crashed.
I'm not trying to piss anyone off, I just thought I'd chime in with my post-crash "forensics"