On a related note, to look at the wiki entry for the feud and related people, there are a damn lot of "citation neededs" at the ends of sentences. So I'm wondering how much of that article was just filled out with information people got from watching the show
Anyway, one of the things I wished had been different was that the two men didn't really meet again before the end. And I mean really meet. Sure they saw each other on the battlefield, but they were just shooting and screaming each other's name. But before that? I don't remember the last time they interacted. Well, maybe that didn't happen historically, so I guess it's good if they stuck to the real events.
It's funny, though (and by funny I mean horribly tragic). You may realize it earlier on, but it becomes most visible in that final battle. Hatfield fled from one war, sick of all the fighting and death, wanting to find peace, but all he found was another battlefield on his doorstep. And McCoy...well, it seemed that war never even ended for him.