"What did they do to Scientology?"
Their action against Scientology resulted in Worldwide protests and a great awakening to the dangers and scandals of Scientology. Anonymous didn't bring them down, but they weekened them greatly.
"I am going to again play my broken record - we should be VERY CAREFUL about aligning ourselves with this group."
I certainly don't think XJWs should align themselves with Anonymous. We are very different groups with different cultures and philosophies. However, our goals do overlap. We can provide information to help them avoid certain mistakes and be more effective. We can also use this as an opportunity to bring more attention to the dangerous policies of the Watchtower Society that need to be changed.
Anonymous action may result in the release of a huge amount of information that could be used for both good and bad purposes. I think it will be largely up to the XJW community to try to use that information responsibly and prevent some of the damage that might otherwise happen.