However, this does not mean that we can say that any other given view is just like atheism in this respect and thus hold beliefs in the face of expert disagreement, that would be far too convenient.

Of course not; the substance of one's reasons for disagreeing matters greatly. In this case, I suspect there's probably a significant amount of correlation/non-independence between the reasons for believing atheism and believing something like moral non-realism.

One thing we should take away from cases like atheism is that surveys probably shouldn't be interpreted naively, but rather as somewhat noisy information. I think my own heuristic (on binary questions where I already have a strong opinion) is basically to look on which side of 50% my position falls; if the majority agrees with me (or, say, the average confidence in my position is over 50%), I tend to regard that as (more) evidence in my favor, with the strength increasing as the percentage increases.

(This, I think, would be part of how I would answer Yvain.)