Horseback
Nice observations and I would agree with your assessment. You note the rudder boost tab reversal mod (from boost tab to anti-boost tab) on the P-51 and its effect on rudder use but you didn't note the same change was made to the long-tail P-40's rudder with the same result. Something else that I have difficulty with is all Mustangs seem to be able to snap the wings off in a dive with the same ease when there should be a very noticeable difference between elevator bob weight modded and un-modded aircraft. (Elevator bob weight mods were also installed on Spits starting with mid Vb.)