Dave,
Nick actually flew the ABC so I think he'd have better information than I do.
I believe part of how they solved the retreating blade stall/bending problem was with a huge hinge offset (25-30%?)and very stiff blades.
There's some other magic wrapped up in that aircraft that nick would know.
And I didn't know that it had inflight blade contact, thanks I guess and sorry several years too late.
tom