Roughly speaking, I would predict a bunch of traits related to cognition (largely related to being more deliberative) and moral motivation (e.g. empathy) would likely be correlated. Another way to think about this would be as tracking the effectiveness and the altruism respectively.

On the cognition side: Need for Cognition (which we already tested in the 2018 EA survey and found that EAs scored extremely highly on), Cognitive Reflection Test, reflection-impulsivity and the Actively Open Minded Thinking scale, and possibly other things which are components of the Rationality Quotient. Higher Maximising and Alternative Search tendency.

On the moral motivation side: potentially higher Empathic Concern from the IRI (we tested this in the 2018 survey and nothing jumped out). I think it's possible that the Empathic Concern measures track too much of the purely intuitive or emotional side of empathy (see Bloom), rather than the pure construct of compassion, or being motivated to help people. It also seems possible that EAs (on average) place higher importance on morality in their self-identity. I also expect there to be some things which crosscut to the cognitive and moral-motivational groups here, for example, systematising versus empathy and people versus things.

My sense is that these two sets of things, roughly speaking, each contribute to making people more inclined to to be more utilitarian. So I would expect measures of utilitarian thinking, like the Oxford Utilitarianism Scale to somewhat pick up on these. I don't think this implies anything particularly strongly about whether people who explicitly adopt a non-utilitarian philosophy can be EAs or whether there is any logical conflict, since I think we should distinguish between the psychological tendency to think in a utilitarian (or more strictly speaking, consequentialist) way and explicit endorsement of the philosophy of utilitarianism or anything else (since most people don't explicitly endorse any moral philosophy).

Also, although people talk a lot about the big five and we have used that before, I think if we used to the closely related HEXACO six factor model, then Honesty-Humility would also likely be correlated.