I have to wonder when Durkon will try to Speak with Dead or even Raise some of them. Mind you, an epic level necromancy spell probably wouldn't leave much evidence, even to one of its victims with maxed out Spellcraft, but at least it would up the defenses again.
As for the pacing, I have to agree about that last arc, but things have really picked up a lot since then, even without accounting for the kickstarter sprint.