i hated the most about Arma helicopters.. the inability to yaw left or right when you are at cruising speed..
The loss of yaw control authority at higher airspeeds is a real phenomenon for helicopters with tail rotors. I can't speak to how accurately this is modeled in Arma2 or in Take On Helos, but I would not expect to be able to yaw a conventional helo at high speeds. Even the Black Shark with its coaxial rotor system only has yaw control authority up to 80 kph or something like that.