No one will ever know, but Lu might have already saved one or more lives, just because some Robinson pilots may have shown a little more respect for the limitations of the craft they are flying.
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Lu,
You are concerned about the Robinson blade tip coming so close to the tail boom that an incursion occurs. Here's a little something that might take you a couple of inches closer to your concern.
Presented with damn little math. 
If the Robinson's rotor is totally unloaded, centrifugal force will cause the two blade tip and the two coning hinges to all be aligned in the same plane.
Conventional teetering rotors have a pre-cone angle of about 2.5º. The Robinson rotor has a radius of 151". Therefore, if the Robinson rotor had a 2.5º pre-cone the stiffness of the rotor would attempt to have the blade tips
[sine(2.5) x 151" =] 6.6" higher then they would be without the pre-cone. Of course, centrifugal force will reduce the effect of this pre-coned angle, as it moves out along the span of the blade from the root to the tip.
All things being equal, the Robinson's blade tips will probably be a couple of inches closer to the tail boom than would those on a comparable conventional teetering rotor.
This might get you a couple of inches closer to your objective. Mind you, most men (and women) will think that 2" isn't much to boast about.
