Surely the big issue with the length of the strop/rope/line is that if the bucket flies into the TR it is pretty much game over (as demonstrated here) but with a longer line, the bucket has to be higher in order to put the line into the TR and the damage possibly less (though not ensured) from a strop instead of metal fixings on the bucket.
KJ - I don't think that modern helos fly significantly nose down because the horizontal stabiliser keeps the fuselage more level. The difference between 60 kts and 100 kts is unlikely to be that great but the amount of drag affecting the bucket would be much more significant.
So you have a perfect storm if you have exactly the wrong length line, fly too fast and then handle the aircraft enthusiastically.