See if we can agree on this.
Kor's character had nothing to do with the resolution of "Errand." Over the course of "Errand," Kor's character served only one function, to advance the Klingon cause without mercy. The resolution of "Errand" was all about the Organians and their act of mercy to prevent death on a planetary scale.
In "Dove," on the other hand, victory was about changing minds. Mara and Kang made choices, first in Mara's case to cooperate and bring the case to Kang, and then in Kang's case to go along with Kirk, cease hostilities, and join with Kirk to defeat the Pinwheel of Doom. At first, neither wished to cooperate because they did not trust Kirk. Plus Chekov tried to rape Mara, confirming her worst fears and the propaganda she'd been told, as discussed in the episode.
Kor might have exhibited nuances, but his choices did not affect the outcome of his episode, except in a single direction. Mara and Kang, on the other hand, had the freedom to help determine the outcome. Furthermore, the choices they made defined the Klingons as, basically, people not at all unlike Federation people, not in just words, but in action.