Dave,
At your target weight a ballistic recovery system (or two) should alleviate some of the concern regarding reliability, at least for test flight.
A well designed safe area for the squishy thing (pilot) operating the controls will help too.
I'd think also that a rotor governer could be replaced by a sprague clutch setup at the right place.
Engine power direct to main gear reduction and then a sprague prior to splitting the mechanical power. The only differance would be that the rotor rpm would have to be adjusted to allow it to drive a small set of gearing in autorotation. This would also allow for any mechanical power taps you needed in growth.
What powerplant(s) are you looking at?
Output shaft speed?
Output torque?
Final rotor rpm?
If you have time, not ganging up on you.
I'm trying to imagine what your helicopter will sound like.
