k/d alone does not tell the story. Of all the planes listed, the Spit XIV is the one people are most likely to actually attempt to FIGHT with, instead of cherrypick. It is also the plane most likely to be taken up by inexperienced folks who are mistaken about its capabilities.
These threads always compare the SpitXIV to the K4 and thus end up as better arguments for perking the K-4 than unperking the XIV. If the Kurt didn't have its difficulties with views, guns, and elevator lock-up in dives, it would CERTAINLY deserve to be perked, and maybe does even with those difficulties. In any case, no such comparison is a good reason to unperk the XIV.