Raw aircraft capability + a fully competent pilot > individual skill. Same planes? Sure, individual skill matters much more; but, different planes where one has a clear advantage? It doesn't matter how good a pilot is if the other guy only flies to the strengths of his dominant aircraft.
Right, but, as you well acknowledge, the situation at merge MATTERS. Indeed, as often as not, I encounter Mr. Spitty when he's got an alt disadvantage. IF I could hit him on an early pass, THEN his advantage would be nicely nullified by the resultant damage.
The ability to reliably hit the moving target from the moving platform was / is where I suspect Grizz excelled, though I'm also certain he was no ACM slouch, having seen him in his K-4 surrounded by reds on at least a couple of occasions. As Mannock said (IIRC), "fancy flying never killed anyone".
Co-e (potential and kinetic accounted for), "fully competent" - of course you're right, subject to an objective definition of the term in quotes - the a/c with an overriding advantage will win.