Uhh, didn't they actually do just that? Why do you think the military flies UH-60's now and not UH-1Ns? Why are they developing the UH-1Y? Seems to me that if the 2-blade system was so great we'd still be using them. But what do I know...
You don't appear to know, much, FH1100, or you deliberately attempted to misunderstand my post.
Mast bumping was known issue in 1960's.
I trained in Hueys in early 80's.
Navy was still flying November Hueys well after the year 2000.
(A guy I know dinged a November tail pylon in Texas a few years before they all got retired).
The US Marines were still flying Huey's in COMBAT in 2004 (when I had a chance to participate in operations), typically in a two ship mix of one Cobra, one Huey.
The AIR FORCE is still flying TH-1H Hueys, and UH-1N Hueys, even as you and I speak. Those aircraft are expeced to be in service with USAF until 2020 something ... but that last is subject to change.
So, NO, "they" didn't actually "do just that," nor did they do it "due to "mast bumping" as a motive.
The Army bought the Blackhawk for a lot of reasons, which included more durable, more crashworthy, and more payload ... but that's a discussion for another time.
Cheers, and Merry Christmas
Lonewolf_50