Sorry Espresso if I took it the wrong way, I am in agreement with you on the subject that in air heli damage is missing. I think that causes sim problems.
If you can't damage the heli (in the air) this lets you put the heli in unusual positions where it behaves a lot more wierdly because you totally exceed the limits of sim model. This is bad because it feels random. It would be better if parts of the heli would break off and then you would have a new aerodynamic model to deal with.
As far as the yawing at speed *note:I am not a pilot* it feels like at 200kph on any heli with stablisers or a big fin at the back that yaw should not exceed 5%. If you wanna yaw you gotta climb (bleed speed)and then yaw (like they do in all the youtube videos).
Worldsprayer I have been experiencing the odd velocity changes but it is hard to pin them down.