I'm just a bit beyond the same stage you are (late in PPL training hoping to do the checkride in the next month or two), but like you I've read a bunch of stuff beyond the basics about how these things actually work.
Clearly you can vary the landing point, but that involves NOT flying at Vy. Glide ratio is (speed)/(sink rate) so anything that affects both equally (like R and omega in the formulae you quote) cancels out - insofar as those formulae go at least.
I suspect that the formulae oversimplify - if they WERE true, so would the result be (for the BEST glide slope). But they don't seem to take into account parasitic drag, which presumably varies quite a bit from one type to another (think Pitts or Stearman to high-performance glider).
I've watched my instructor fly two autos in succession, one at 20 KIAS (with a strong headwind and we were going backwards) and 100% rotor RPM, and one at 90 KIAS and 90.001% rotor RPM (R44) and the results are VERY different, that much I know. 90 knots is way above Vy but clearly gave much better results (assuming you WANT to go a long way of course).
Personally I'm at the point where I can just about nail the numbers for a "textbook" auto but I'm not encouraged to mess with things. That comes later assuming I can afford to keep flying the thing! Though I did do one "maximum range", I was somewhat terrified with the rotor horn blaring and the needle hovering (of course - this was a heli after all) on the lower redline, but it did work.
n5296s / n9888s