Kurt, whatever you may want to be getting at, the fact remains that using flaps for turns is the standard procedure to engage enemy planes in US planes now.
All planes have their limits in the AoA which, if you cross over, you will stall. Planes react differently on the verge of the stall, but some planes react extremely making it easy to handle, while others react benevolently.
Start a turn at 150mph in a P-51 or a P-47, and then gently stomp full rudder to the direction of the turn. The plane holds a tighter turn radius.
Try that in a Spitfire, and the plane initially holds a better turn radius, then slips into a flatspin as the speed drops down.
Try that in a 109, and the plane immediately starts a snaproll.
So okay, Bf109s and Spitfires are light planes with high torque. But what about the P-51s? They weren't exactly torqueless aircraft.
The thing is, all US planes feel like the P-38 now, and to go a step further, maneuvering in the P-51 or the P-47 feels like playing IL2/FB now. The "mushy", "stable", rocking around and maneuvering at super low speeds with flaps out, not much worries about destabilization or torque.
I've tried maneuvering in the 51 or the 47 without flaps to see how much difference it makes, so I'm pretty sure the difference comes from flaps. Whatever is the special ingredient in the flaps that enables the 51 or 47 to do that at 120mph, is not working, for the other planes.