"You use the retreating blades and reverse velocity to add to the overall lift."
OK, but you still have to operate blade away from optimum AOA. My point really is that you get no performance benefit (likely a performance detriment) over the intermesher, for the added complexity of two additional outboard gearboxes and drive shafts. The failure of any one of these makes the arguement "academic" - there are a lot of posts on this forum about tail rotor loss of drive...
Mart