@GoodGrief: in the 32 years since the article you cited came out, the semi rigid, underslung, teetering rotorhead on the Jet Ranger has not caused a rash of deaths due to mast bumping. (That design is similar to that of the Huey). The Navy's still flying them at Whiting field (though there have seen better days).
Plenty of two bladed Hueys and Cobras were operated safely and effectively for the 30+ years since the falling firmament articles linked. Heck, they are still being flown, the Air Force with a TH version, even though the Marines are replacing them nowadays with the newer, 4-bladed UH-1Y (Venom) and AH-1Z (Viper) that use bearing-less rotors.
I realize that this thread is about Robinsons, but just thought that I'd report to you that the sky hasn't fallen even though some helicopters now and again fall out of the sky. (Not to mention all of the 212's that have been successfully operating the world over ... )
Some flying basics usually help us operate our aircraft within limits:
You don't pull nine G's in a Cessna
You don't unload the head on a Huey.