If neither Rocksteady nor Dini are in then I don't see how exceptions could be very high at all.
Dini isn't a great loss. Arkham City
is a great game, but the writing and plot structure are easily its weakest links (unless you're a fan of relentless misogyny and Jeph Loeb-style "shove everyone into the story regardless of whether it makes sense" plotting).
For a video game, I don't mind that kind of storytelling. All it means to me is longer game play!