i have about 1300 hours on 135s, never noticed any lack of tail rotor authority. ECD issued a pilot circular following an enquiry about LTE in fenestron helis, they maintained that if you have what you perceive to be loss of tail rotor effectiveness that full pedal input (to stop) will rectify the situation. Other than that im not sure what the b0-105 driver was referring to. Then again im no test pilot, seems like a question for those guys 'pushing the envelope'!!