The EA Forum and LessWrong obviously share a lot of features, members, and topics of interest. I've recently started posting to both, and find myself often wondering what sorts of posts should be posted here, vs posted there, vs cross-posted to both. What are people's thoughts on that?

One specific subquestion is how often, and under what conditions, cross-posting to both is a good idea? It seems like cross-posting is relatively rare, even for great posts that seem like they'd be of interest to both forums' communities. This makes me worry that me regularly cross-posting would be spammy. But obviously anyone who saw the post on the other forum already can just not click, so maybe it's silly to be worried about being spammy?

And another specific subquestion is how much overlap there actually is between each site's members. Does anyone know, or have a vague sense of what the proportion might be?

I briefly searched for relevant prior discussion, but only really found this from 5 years ago:

I expect that at the new [EA] forum, as on the effective altruist Facebook and Reddit pages, people will want to discuss the which intellectual procedures to use to pick effective actions. I also expect some proposals of effective altruist projects, and offers of resources. So users of the new forum will share LessWrong's interest in instrumental and epistemic rationality. On the other hand, I expect that few of its users will want to discuss the technical aspects of artificial intelligence, anthropics or decision theory, and to the extent that they do so, they will want to do it at LessWrong.