I have to admit that I only browsed the thread, but a few comments come to mind.
*One,
chopping throttle in a luftberry situation is a no-no. In sustained turns, your biggest enemy is lack of thrust, because if you are sustaining a high AoA, you are buring all of your thrust energy with drag. Slowing down kills your rate of turn.
*
Slowing down does not automatically reduce your turn radius when you're in sustained turns. To the contrary, your radius deteriorates.
Note the turn radius scale denoted by the black diagonal lines. At corner velocity, the 109G at 240 mph can pull a radius of about 640 ft. Down at sustained turn speed, it's turn radius is close to 700 ft. The exception is if you are slowing down to deploy flaps. This changes your foil shape, and therefore changes your turning capibilities. However, with that said, depending on the airframe, it is likely that slowing down to deploy flaps will also deteriorate your rate of turn.
*
Turn radius will not always determine the outcome of a fight. Especially when it comes to a luftberry scenario. The plane that can travel around a 360 faster, can beat a plane turning a smaller circle.