It would appear that 52 knots and 69 knots, more than just being secret info, found their way to the RFM.
There was reference in a previous post about weight. Doesn't weight effect the sink rate but not the glide distance?
Assuming the wind is not fixed in velocity, won't its influence on ground speed be constantly changing. Rather than trying to make a series of calculations with your head inside, wouldn't it be better to just look outside as to how the spot is moving on the windscreen and use airspeed, rotor rpm and trim to achieve the best possible glide path. Last time I was at Bell, Kevin Brandt did the whole session of emergencies in the 407 with the airspeed indicator covered. That exercise really reinforced the spot on the windscreen concept.
Finally, an instructor from Canadian Helicopters and friend, Tim Simmons, told me some years back that it is far better to make a good auto to a bad spot than a bad auto to a great spot. That one has stuck with me.