A sales pitch ????. 
slowrotor,
"I wonder about your preference for intermesh. Why not coaxial?"
The intermeshing has a number of advantages over the coaxial, particularly when considering future high-speed rotorcraft. A post in 1993 by the knowledgeable Paul Cantrell looked at the question from the opposite perspective:
"I know the ABC is currently shelved, but I hope that it will started up again. I wonder whether intermeshing wouldn't work better - perhaps Sikorsky didn't want to have to deal with Kaman? I don't really know why they picked coaxial rather than intermeshing..."
"I would be concerned with gear mesh failure in a synchropter. "
This is an advantage. There are hundreds of potential failure points in a helicopter. The interconnecting final reduction is a short-coupled two gearset, which is intentionally over designed.
________________
quadrotor,
"... a blade collision ..., as the blade's tips would be almost in the same plane...'
This is one of a number of reasons for implementing Absolutely Rigid Rotors. The intermeshing feature is the only significant commonality between the well-known Kaman helicopters and the UniCopter project.
IMHO, Kellett was on the right track with his 3-blade rotors. He was seeking one million dollars to produce a rotor with greater rigidity. It appears that the death of Dave Driskill ended any chance of getting the funds and ended the company.
H-43 is a Kaman pilot, who has posted information about the Kaman helicopters on this forum. If interested, a search on [H-43] and [Rotorheads] should bring up his comments.
Dave