My point was to prove that the K4 is matched in climb or speed by other non-perk plane in the game and the graphs prove it.
And my point is that you ignored the rest of BoilerDown's statement, which is: "What makes the K4 such an easy choice is that it doesn't matter what everyone else is flying, the K4 is better than it in the same two ways, only the degree of better is different." You showed how the K4 was matched along one dimension, but you didn't show how other planes were better in both ways.
BoilerDown's statement is an exaggeration, but his basic premise rings true - if the K4 is matched in climb by a plane, it outmatches it in speed, and if it's matched in speed, it beats it in climb. That makes it an extraordinarily versatile plane. Not easy to fly, per se, but definitely versatile. The rest of your response simply downplays the advantages of a 109 (it has far, far better low speed vertical handling than a Spit XVI and more forgiving stall characteristics) and overstates the strengths of the Spit XVI.
Note that I didn't suggest that the K4 is better than the Spit XVI overall, because I don't think that's a fair statement. It's just not insanely worse as many like to suggest.
But back to what I stated originally, I think the popularity of the K4 is more to do with a few top sticks flying it rather than any of its 'merits'.
It's both. The top sticks fly it because of its merits, and people who see how well they do with it try to emulate them. I always enjoyed flying planes that fit my style of playing, and I suspect that the same is true for the K4 experts. It's versatile and has a lot of cool things it can do with practice. It's fun and can control most fights. I'm not surprised at all that players gravitate to it.
so grizz in a p40B > than most in anything.
Grizz in a P40B would get frustrated pretty quickly at the plane's lack of lethality. A lot of his flying style, from what I've seen, involves setting up for a passing kill shot. He's willing to take major risks in positioning in order to set up the perfect shot on a pass. That doesn't work with a P40B. He'd be very, very good in it, but it's not a plane that allows him to fly to his strengths. That's not a slight on Grizz, more like a compliment to the fact that he matched his skill at setting up angles and his penchant for hitting snapshots with exactly the right plane in the K4.