Ardy: my QPM chart includes proxies for instantaneous turn radius and excess energy for sustained turning. Generally the lower down and to the right an airplane is, the better the turn radius. The more up and to the right, the better the excess energy for sustained maneuvers.
Tango, I see your point. You make no distinction b/w the "energy" and "angles" fighters of E-M diagram analysis but rather rate how much overage each has in it's particular forte. This makes decent sense yet I agree with Ardy that energy fighting a s a rule is more demanding of the pilot since it requires at-times counterintuitive maneuvering (i.e., I agree the knee-jerk noob thing to do is to go for angle).
I like your topological approach. You can almost chop the isoperfs (coining here) into an upper and lower for angle/energy. Notably the Spit XVI splits the difference so well that you'd have a hard time binning it.
Why those particular exponentials on the critical synthetic X, btw? The selection of those strikes as unnecessary since I see no correlative fit with X - i.e., why select a synthetic critical x abscissa cut from whole cloth? Those exponents seem to buy you nothing in terms of correlation...
Otherrwise, it's good to see an active mind applying some analytical tools.