too many variables
Engineers, in the confines of the lab, can come up with many ways to affect the controllability of helicopters. Unfortunately the variables in the field more that counteract their plans. Start with environmental conditions. The real weight of the aircraft. Rigging by mechanics 1 thru infinity. General differences in the materials used to create the machine and the subtle differences created over time on each component. If you have SAS etc. the differences electrons make over time on each component. In the U.S. army i could fly one of fifteen to eighteen different UH-60's in several months time. Different years, different total AC times and yes, different components installed in the same series of aircraft. The system on the A model 60 was designed to hover with no pedal input at 16,825 lbs. No one will ever convince me that it worked that precisely so what I did was I did what I had to do to keep the nose pointed where I wanted it. This year I have been signed off to fly the R44, AS350B2, EC-145 and BK117 A and B model. They are all different and initally I didn't like any of them, generally based on the difficulty to hover comfortably because of the differences in tail rotor control. After a few short hours I have that figured out and can then move on to the other things I don't like about each one. ie BK cyclic trim system. ( I took my checkride on the BK today and I am sure I will warm up to the system soon) The bottom line is they are all flyable in their own way. All the science and engineering is nice but eventually its in the hands of the pilot and we make the best of it. Does the EC145 really fly any better that a UH1H? Cheers