I want a meta-ethics that gives me some comparative advantage in dealing with moral problems, as compared to other sorts of disagreements.

This may be a case where not getting it wrong is the main point, even if getting it right is a let down.

My own view is quite similar to Luke's and I find it useful when I hear a moral clam to try sorting out how much of the claim is value-expression and how much is about what needs to be done to promote values. Even if you don't agree about values, it still helps to figure out what someone else's fundamental values are and argue that what they're advocating is out of line with their own values. People tend to be mistaken about how to fulfill their own values more than they are about how to fulfill their own taste in music.