As for dark...well, at the moment I'm about ready for some lightheartedness! There's a good proportion in the series as a whole, but the last few episodes have been pretty brutal.
A little angst is good for you! I think the next couple ought to be pretty light - you've met their sensei, yes? She's pretty good comic relief.
Maybe there's something wrong with me, but I like the bleak brutal episodes as much as the funny ones...