maybe i should use the word inertia rather than momentum but what i am getting at is these ...
when you move the controls the forces on the control surfaces move the aircraft this is not an instant thing i.e. full stick left does not result in full roll left instantly, there is a lag as the mass of the aircraft gains momentum. reverse the input instantly and there is more lag as there is more opposing inertia to overcome by the forces on the control surfaces. the more inertia the more time is lost.
planes skid, throttle changes do not result instantly in increased speed, roll are not reversed instantly even in good rolling aircraft, i think the smaller lighter planes have an easier time with all these things simply because they have less inertia to be moved around by the fluid air and the force it can apply.
control surfaces, props, and airframes are not 100% efficient, extreme input changes do not result in extreme direction changes instantly and the more inertia or momentum to over come, the more delay there will be while these things over come the inertia of the aircraft. i think smaller lighter aircraft are "quicker" or more nimble because they are dealing with less inertia, and that has real word consequences for over all maneuverability.
why would i show the math when it is the math relative to the real world that i am questioning ?
i think i understand where you're trying to go.
you think that because(i'm using these as examples, because i've flown both in here) the p38 is in the ballpark of 11,000 pounds, with a 54' wingspan, that it cannot possibly turn even momentarily with a hurri2c, weighing about 7,000 pounds with a wingspan of about 35'?
the hurri rolls much more crisply than the 38. it can pull a tigher flat turn.....with ease. but suppose that 38 is 600 on your 6, you're both doing around 300 mph flat and level. you roll 90 degrees right, and pull hard, into blackout. the 38 driver sees your aielrons deflect, sees your hurri start to roll. he knows without a doubt, that should he try to follow, he will lose.
so what is he to do? he pulls back slightly on the yoke, as he applies some right aileron, climbing, bleeding speed, keeping you in sight. since he's now tilted the lift vector of his 38 some 30 degrees off of the vertical, he's turning along with you. now, you lighten up your turn, to avoid bleeding too much "E", and the 38 driver kicks a little right rudder, dragging his nose down. now he's accelerating hard, and closing right onto your 6 again.
now, naturally, since he only gained a few hundred feet, it wasn't very obvious to you, so you think he MUST be doing something gamy. you try it in the other direction, and get the same result.
this is part of what a lot of people are trying to tell you. you cannot take any single piece, and proclaim something is wrong. we all use all we have to try to win the fight in our cartoon airplanes.
i've had guys in fw's try a forward slip to force me to overshoot em. it's worked a few times, as it's hard to recognize(to me anyway) before you've already blown by him.
try thinking in 3 dimensions, not 2. it is much harder than it sounds.