I didn't vote because my vote choice would be something like, "I'm really skeptical about the change, but let's see what Brandon does with it."
I'm skeptical for two reasons. First, I'm confused about the reasoning behind the change. From Brandon's remarks, he seems to think it's a minor detail that will make hardly any difference--maybe even no difference--in subsequent books. But then he also says that it's important to make the change to be more in keeping with Kaladin's character. Well, which is it? Important character issue or minor editing detail? (The answer is that it's both, I suppose)
On top of that, I don't think Kaladin was actually acting contrary to his character--or his Oaths--in the original version. His goal is to protect Dalinar, and it has been proven that Dalinar "cannot protect himself" from Szeth, so Kaladin's Oath not only justifies his pursuit of Szeth, it obliges him to act. After the armies disappeared from the round plateau, Szeth said straight out that he knew where they went and took off. Kaladin realizes that the danger to Dalinar hasn't passed, so he has to give chase.
After their brief conversation, Szeth comes to the realization that he's not Truthless and that he wants to let himself die. He could have dismissed (or thrown away) the Blade, or slowed his flight, or just said, "Hang on a second. I'm not going to kill anyone but myself." He didn't do any of those things. He kept flying toward Dalinar, and kept his Blade (seemingly) at the ready to confront Kaladin. By all available evidence, Szeth is continuing in his course of action, so Kaladin has to continue to in his, and so he attacks. Szeth declined to parry Kaladin's blow, but for all Kaladin knew, that may have been a gambit while Szeth prepared a counterattack.
Sure, it's pretty obvious after the fact that Kaladin killed a man who wasn't a danger to anyone, but he couldn't have known that at the time. Anyone who say that Szeth "could not protect himself" is ignoring the Blade that he was still holding. Maybe Kaladin would regret what happened, but then again, Kaladin regrets not saving every single soldier he's ever met. Besides, it could lead Kaladin to reflect on the meaning of his Oaths, which would probably be an enlightening exercise for him and for us readers.