Dave, I looked at the Kaman K-Max, very interesting helo.
Two intermeshing rotors, each 2 bladed with apparently solid rotor hubs (fixed to mast, no teetering hinge), and drag hinges.
Flight control is all done by servo tabs. Yaw in the hover is accomplished with differential torque through differential pitch at the rotors affected by the pedals. Forward/aft cyclic is accomplished by pitching both rotors foward/aft. Lateral cyclic is accomplished by affecting one rotor only, cyclic left causes the left rotor to tilt. etc. The pronounced airframe pitch caused by collective pitch changes (apparently common in intermesh designs) is compensated by the horizontal stab.
It has a total payload of close to 140% of empty weight. It has a HOGE of 26,300 feet (at what weight I'm not sure), wow. Rotor disk loading is low, so weight lift is high, and noise is low.
Have you thought about servo tabs? It's simple, light, and not too complex. Requires flexible rotor blades though. Also, your website shows 2 possible ways to control yaw. How about differential for/aft rotor pitch controlled by the pedals? Might not be too effecient in forward flight, but could transition to a rudder on the vertical stab for that. Could also roll the airframe to the wrong side in forward flight, so not so coordinated in the turn.