I can tell you that this is not "authentic". I am a real world helicopter pilot with quite a few flight hours, and I can tell you from experience that your tail rotor has authority at all airspeeds. You can damage the helicopter if you apply full pedal above certain a airspeed, but the helicopter will still behave accordingly. Your tail rotor's primary job when you are above ETL is to maintain coordinated flight. With no authority beyond a certain point, it is impossible to complete maneuvers like a pitch back turn, or a RTT, or even a stop turn due to the limitations.

"Above a certain speed the wind is flowing over the aircraft too fast for the tail rotor to make any difference, this is also why certain other flight hazards decrease around this speed."

What does this mean, what other flight hazards are decreased? Why would the wind make the tail rotor stop doing its job, sounds counter productive if you ash me.

You can disagree with me if you like, but it does not change the fact that the tail rotor authority is legitimately unrealistic.

Also, if you do a run on landing fast enough for the gear not to deploy in the CH-49, the helicopter will sit the same height above the ground as if the gear are down and no damage is done to the helicopter until you reach an airspeed that the gear would normally come down. I will create a separate issue as well.