I’m going to address this again because I think I can do a better job after thinking on it a bit.
Adjusting the fletching. I think you’ve missed the issue I was addressing. Typically those advocating high FOC arrows point out that you can shoot with less fletching. In calm wind this is true. Moving the center of mass forward increases the length of the lever to the pivot point that the fletching can act on, and decreases the length of the lever that the broad head can act on. This means that smaller fletching can control the broad head. You said that decreasing that decreasing the fletching would result in less broad head control. Technically that’s true, but increasing FOC reduces the amount of fletching required to get equal broadhead control.
BUT I’m starting to think that the high FOC guys have something askew as well. Whenever someone complains of the arrow’s flight in wind, I’ve heard them suggest reducing the size of the fletching, and explain why you don’t need as much fletching. That’s all fine and good for calm conditions. The issue is that not every complaint I’ve heard or read regarding shooting high FOC arrows in the wind is simply a complaint about how far the arrow drifted. I remember one specifically on Kifaru cast, and have probably heard some elsewhere, that was referring to the knock end of the arrow not following the point end of the arrow. Basically poor arrow flight. The problem is, the arrow was properly tuned and shot perfectly in calm conditions. The fletching steers the arrow because of the pressure from the air moving past it as the arrow flies FORWARD. When wind pushes a balanced arrow, the arrow remains properly oriented tip to tail as it drifts in the windward direction. When wind pushes a high FOC arrow, the tail is often pushed more than the point, and thus you have poor arrow flight.
I THINK there is a solution.
I THINK the Ashby guys may have this backward. You need more steering from the fletching in the direction the arrow is traveling. The answer is
MORE FLETCHING. If the forward velocity of the arrow, and the velocity of the crosswind were equal, then the fletching could not correct the alignment of the arrow’s shaft to its flight path, but unless you’re shooting a long bow in a hurricane, we don’t have that problem. The air flowing over the fletching from the forward velocity of the arrow can apply more force to the fletching than the air pressing on the side of the fletching due to the crosswind. You just need enough fletching there.
My opinion is that high FOC arrows probably need more fletching than low FOC arrows to correct arrow flight in high crosswinds.
NOT TO STEER THE BROAD HEAD. They need less fletching to steer the broad head.
To your last point, getting the entire arrow shaft to fly in line with the broad head contributes more to penetration than a high FOC. That’s probably why Ashby’s experiments demonstrated that, and probably why he lists arrow flight ahead of FOC.