IFMU, Dave has a point in that if intermeshers had been developed with the same vigour as MR/TR then high speed helis
may have occured sooner. In truth with X2 pointing ABC technology towards the market place, i would say the two techniques are converging. It is almost accademic to worry about exact layout of counterrotating rotors, as long as they are there to counter retreating blade limitations. As for tail rotor, well turn it 90' to make a nice pusher prop.
Dave, i can understand from the comments i made several posts ago why you might be drawn towards interleaving as a solution for lateral stability. My concern with this is that you are now introducing distributed drivetrain for flight critical rotors, which pushes up component cost & mass if nothing else. Also the increased frontal area will reduce highspeed performance - in a fixed wing most of the profile drag comes from the wings, not the fuselage! Going to ABC tandem would improve drag, but not driveshaft reliability.
This is why i am keen for X2 to be a success. It's only real detriment at this stage is the loss of payload for additional rotor mass, which reduces return rate for more expensive config. In practice each rotor need not be as strong as single rotor it replaced, for any given manouvre, sincle load will be shared between two rotors. Additionally twist & taper will be optimised for highspeed not hover, which is why IRTC intermeshing still has a look in. The symetrical control you seek Dave is already present in coaxial.
Now if, after all this, X2 did not see the light of day? Well
Mart