Since anyone flying one of those planes trying to boom and zoom you is a horrible pilot, they are harmless to you and a non-issue.
Since Spits and N1Ks *never* run, everyone still has plenty of targets available.
Seriously though, the only time I run into difficulty with runners is when I'm tooling along in a SpitVIII or the like. Sometimes I latch onto the long six of a Mustang or similar, and low and behold, they extend away. I suppose I should be indignant and filled with anger that they did not reverse back into me and give an easy kill.
Bluntly, if you have a major problem with targets running away all the time, you are probably in a ride that trades speed for maneuverability. That is a limitation you chose to inflict upon yourself, and whether you overcome it or not is purely up to you. Perhaps guys who fly P-51s should complain that other planes turn too tightly for them to follow, its "unfair". Perhaps guys who like to fly P-40s should complain that the 109s have too much horse-power and its "unfair" how they leave them in the dust in the vertical. This would make about as much sense.
Also, it is not a matter of planes. The SpitXVIs are as likely to "extend" from a Hurri as a P-51 is from a Spit in my experience. But I don't consider this unreasonable. I've also known P-51s to run from Doras...here the point is not I suppose to win the race long term but to drag you to ack and under friendly forces. Oh well, I've learned not to chase runners who are obviously dragging me to a trap. Perhaps there would be less wailing and gnashing of teeth on the boards if everbody did the same.
Kinda limits my choices on what I can fly.
Nothing limits your choice on what you can fly. If no one in a bnz plane is attacking you, they are just scenery. If they do attack you, there is always a window for an overshoot kill. It may be short and require exceptional gunnery skills, but so what? This is similar to how the firing window to kill a much better t'n'ber in a bnz plane will often be short and require exceptional gunnery skills.
I have seen people argue that if the energy fighter takes his shot, his gunnery skills are inadequate, and he ends up with a superior angles fighter on his long six, he should reverse back into it and die. But one could also argue that if the angles fighter generates an overshoot and fails to get the kill before the energy fighter has extended, he does not deserve the kill because his gunnery skills are inadequate.
Of course, both notions are utterly false IMO, because there is no use pondering the question of "deserving" something, there is only the question of whether you can GET something. If you can build a little alt and then dive in to execute that Pony with your Spit, sucks for him, bully for you. If the Pony can get out of it by running, sucks for you, bully for him. Same thing goes for all these little complaints people like to air.
Honestly, if the opposition LIKES the way you are piloting the plane, either you are coming up on the short end of the stick a lot or the enemy is a masochist.