Joe, I appreciate the good discussion.
You are correct it the fact that if you accepted to fly at a tilt, you would not need to hold the stick. If you have adjusted the proper rotor disk tilt to compensate for engine torque, then as well your stick is flying in the neutral position and should need no correcting... until you reduce engine torque.
My point it that most pilots, including myself, will not accept flying at a tilt, and will correct after power reduction, and therefor hold the stick into the position that corrects the tilt.
It is my belief that if you had a twisted HS, the airframe torque would change with airspeed, and you would have no neutral stick position throughout a larger parameter of the flight.
True, that due to Bernoulli's principle the propwash cone of airflow will taper inward becoming smaller in diameter and as such accelerates in speed, but I disagree that it increases in rotation after doing so since their will be a fuselage in the middle of the stream and between the engine and the HS.
In Michael's case as we are discussing, we are not just dealing with propwash, but we are dealing with variable airspeeds influencing the desired effect on a twisted HS to solely counteract engine torque. I have flown tractor gyroplanes, not enough to be any kind of an expert, but enough to have a feel for their vulnerabilities.
Theories are one thing, but reality is quit another. Whenever an airfoil creates lift, it create drag, that is a fact of nature. I understand how you are saying that by untwisting the propwash should neutralize the drag, as I don't fully agree, but my point has been that there is more going on with the added airspeed effecting the twisted HS that is not being accounted for.
As a real-life example, any time we are flying an airplane, and add aileron control, the airplane will loose airspeed due to the increased drag. The same thing would happen on a twisted HS.