I’m delighted to find this simple but very effective mod. At last I can actually hit stuff!
The previous wobbly head effect was making it all but impossible for me to line up the sights on anything. Though not a pilot, I have been up in open cockpit biplanes a few times, as well as in some jet trainers, and in my recollection I was always able to hold my head quite steady even if the pilot was throwing the plane about a bit. As Nowi says, you quickly learn to “muscle through the curves”.
Also, recall that the original Fokker EI had a rigid “headrest” device to hold the pilot’s head steady to help him line up shots with the machine gun, see attached pic. This device was very quickly discarded as unnecessary, implying that headshake wasn’t an issue after all.
So I certainly vote for Headshake=0.
Mike