I understand what you are sayiing and mostly agree......the one question I would pose to that is if that "demand for more power" is a product of attempting to accelerate too quickly which would not matter if you were into wind or "down wind"....and as I recall Doctor Lappos correctly what he opined is the takeoff distance downwind is far greater than when done into wind and that if the control inputs are done properly there is no difference in the power required for the takeoff but rather just a much longer distance. Note....I am working off my memory of that discussion from several years back and may be mis-stating what he had to say.
The trick with the Chinook was not going sideways....as there is just a wee bit of drag that you encounter doing that.
The trick was to kick some pedal into the old girl so as to rotate the aft head into clean undisturbed air just as you reached ETL with the Forward head which was in clean air all the time.
The alternative method was to have a quartering head wind component so as to accomplish much the same thing.
Chinooks, particularly the early models, could be very limited on power when loaded to or over max allowable takeoff weight.
There were times we measured the weight of our loads by use of the Torque meter alone....if we could pick it up without bleeding RPM with the load at a Ten Foot Hover.....we went....so getting all the advantages were key in getting the job done.
There were times we debated about how to get over a three foot high berm.....so it matters not what kind of helicopter you are flying....you have to be on top of your skills when operating without any excess of power.
The early A and B Models of the Chinook were interesting to fly on a single engine....and in both we had to burn off fuel to be able to get them light enough to do a single engine rolling takeoff and climb away.
The Vy for both was from about 58-61 Knots IAS.....get behind the curve on that and you only went down until you regained that speed again.....and you better have the height to do so or you would be. making an unplanned landing somewhere.
A bit of searching using google found this......
Hovering Downwind