Dave,
I agree with your objectives, and the way you are tackling them (actually seeing hardware helps a lot
). I think your conclusions about general heli layout are well reasoned. However, the market for a product does not usually care how that product works as long as it does. The key for reliability, hence lower operating costs, is always simplicicty.
For this reason i have always felt that counterrotation (in all it's forms) becomes justified only as speed affects retreating blade performance. Flyability is solvable with a simple gyro in the control system of a rigid rotor - quite why this has never come to market in light helis is anyones guess (eg Lockheed CL475). I imagine that when a well trained pilot can manouvre a teetering head like Dennis Kenyon can, there is little perceived requirement.
Rather than trying to convince us all off the merits of counterrotation, and the semantics of which system when, i suggest a different line. You have convinced me that active blade twist is the next big step, but have not addressed the doubts. To my mind, the biggest is the control system required. I would like to see CAD layup of the rotor hub that allows ABT to function reliably. From the view point of cost, i am not convinced about high speed active servos for a light heli - if i'm wrong i'm wrong. I would imagine that the simplest is twin swash plates, perhaps with low speed servo trim for airspeed input.
I think the real future of light helis depends on engine technology (thanks for pointing this out, NL). I am beginning a design study on diesels adapted specifically for aeronautical usage, to scope out the potential for development. The objectives would be fast combustion (for high RPM) and high dependancy on turbo charging for high torque/displacement. From the design study the best i could ever hope for is (say) Cummins to show interest, but it would be an outcome...
Mart