Thanks SlowRotor,
"Putting another rotor above the other only increases downflow and therefor is not as good for autorotation."
Intermeshing can be thought of as a "bunched up" side by side config. Retreating blade goes above other side, and is unloaded by feathering. This means autorotation performance is improved since advancing blade runs at optimum AOA rel TPP. I have suggested tip trim to Dave - this forces tip AOA to 0 in all flight conditions, so swash plate actuates only root (like BERP to some extent).
"Just a friendly reminder, try searching this forum for extensive discussion on this topic"
Quite right, i should have done an extensive search first. I really just wanted a concurrent view on this config, since i have only just finished studying chopper design...
Mart