Switch arming, I can't stick arm with the crazy acro stuff I do at zero throttle!
So, if I leave BiasCorrectGyros=true and zero out the correction factors, it will recalculate correctly before spinning up the motors. I have that set to 500ms as the moment but it behaves just as well at 250ms.
Once armed the modelview returns to level and stops spinning about. After motors have started the iterm windup happens really slowly, I can leave it at 0 throttle until hangtime runs out (I have it overrided to 8 seconds for ground testing) and it won't even lift a corner off the floor, it just eventually wants to yaw one way but doesn't get enough windup to actually move before hangtime finishes.
When BiasCorrectGyros=false it still takes the 500ms delay prior to starting the motors but the modelview does not correct itself this time.
As soon as you pass the min throttle threshold the motors really try hard to correct the quad. As I said I'm fairly certain it would flip if it wasn't being held down.
When I was snooping through stabilization.c I thought it looked like gyrobias would be calculated during arming regardless of BiasCorrectGyros but that doesn't seem to be the case.