I only hold this view weakly, but yes, I’m worried that, as you put it, “E first, A second” people are less likely to stick around.
I don’t think “A first, E second” people are necessarily easier to get in the first place though, as they are more likely to already have a calling (and so to have less personally to gain) and to be committed to other altruistic pursuits that are hard for them to drop as “ineffective.”
That said, I’ve seen significant movement among heavily committed farmed animal advocates towards thinking more about and acting in the interest of maximizing impact… though farmed animal advocates are often already doing that advocacy because they’re already thinking about effectiveness: they see the issue as massively important and very tractable. So I suppose realistically I’m putting most of my investments in people who are A first, but still clearly already E.
Someone who prefers to remain anonymous shared with me that there were multiple issues that made her and other women interns feel excluded at an EA organization, but she felt it was too intimidating to bring them up because the staff seemed too tight, including the women, and the interns felt too separate from them.