ET, understanding of coaxial rotors isn't as thin on the ground as you suggest... it's not a new configuration, there's wind tunnel data, aeroelastic modeling, subscale rotor testing, and of course flight data for several generations of ABC style aircraft. In addition to that, there is the experience of the Kamov, Hiller, and other designs that are to varying degrees, relavant... certainly more than single digit numbers of people are really conversant.
The design will manageably scale. It may or may not be the best fit to customer requirements, but that's partly what the JMR effort is for :-)