I had an issue with mine (4oz Cocoa nibs + 2 vanilla bean) and it'll be green for a long time to come. I have another batch, an oatmeal stout, that I've just added 8 oz cacao nibs and 3 vanilla beans too. I'll have some sort of results in another 4-6 weeks.
I'll be brewing another one this weekend probably. I'm going full cacao powder on it so that I can compare and contrast with the nibs. It's the same oatmeal stout recipe as the nibs, so should be a good comparison.
So, how did they turn out?