I think for the same reason we had meetup posts on the front page, we should just post stuff to the main LW (this will maximize the use case of recruiting new people), and we should move on to creating a sub-reddit only when the volume becomes distracting. The decision theory list can continue to serve the current purpose of a place to discuss particularly arcane ideas (that are not results), which new recruits won't typically understand anyway (and so why waste anyone's time). Publicly opening list's archives (but not subscription, we don't have voting over there to defend ourselves) can cover the rest.

But we might want to adopt a standard tag on LW so that people can subscribe to this part only, which I can commit to consistently setting on all posts that quality, say "decision_theory" (just fixed for this post).