It sounds as though you might not be seeing the potential of those diagrams.
Those Ps curves are useful. That's the energy part of the diagram I've been missing out on. Can you estimate the plus and minus curves once you have the Ps = 0?
That's not to say they don't have weaknesses,
Of course the curves vary with fuel load, usually something you don't know when you face an opponent. Also altitude. I'd like to see a combined flap curve on the same graph with the same scales, like with your Ki-84 / Spit16 comparison. Also with those you have a flap curves for speeds above which the flaps retract, so I gather you have extrapolated those? I would try to make a set myself just out of interest but I can't find a nice blank colour template
Indeed, diagrams like that are valuable enough to be required ground school material for fighter pilots in the most enlightened military services around the world.
Unfortunately they are not required reading at the 'nrshida seat of the pants try to manoeuvre with everything and evaluate afterwards in your parachute' school of air combat. I'm afraid my brain is more artistic / visual than mathematical. I can usually follow the mathematics if I have an intuitive feel for what it is describing in the first place but not the other way around.
Ah the energy egg. Again that would be a lot more useful with a 'centre of weight' position marked, also since we have relatively low thrust isn't ours less egg-shaped and more a procession of raindrop-shaped loops?
Calculating those curves will certainly be interesting for you, and possibly challenging, so good luck with that.
I detect true sadism here
