Part of me wishes they'd just abandon the "no kill rule" for Superman and Batman in the movies. Because it just creates problems anyway. I love Nolan's Bat-trilogy, don't get me wrong... but it almost seemed silly to establish the no-kill rule there because it just creates goofy scenarios. Batman won't kill Ra's, but he'll leave him to die on a train that's about to crash because of things that HE set in motion (which, if you ask me, is pretty much the same thing as killing him). Batman won't kill the Joker, but he'll kill Harvey Dent in the next scene (yeah, it was an accident but still... he had the presence of mind to save the Joker's life, but not Harvey's?). Bruce wouldn't kill that farmer to appease the League of Shadows, but he destroyed their lair, killing most of them and probably killing the farmer anyway.
Now, I'm not saying that they should go the Tim Burton route and just have Batman kill EVERYONE he comes in contact with but maybe relaxing the no-kill rule a bit would be the character's benefit, I don't know.