I'd set it to 1000 or so. For this to work well, there should be some way of seeing and discussing changes, like wiki history and discussion pages, or stack exchange comments (as opposed to replies). For LW, I'd start with something like stack exchange comments (a meta-comment area under a post distinguished by lightweight layout, smaller font, and shifted by bigger left margin), and add special comments that mark edits to the post and post's tags, with a link to the diff ("Fixed paragraph spacing [diff] -- 03 March 2012 08:30:42PM by Konkvistador").
like wiki history and discussion pages
Speaking of which a clever integration of LW and its wiki would be very beneficial.
A while back, I polled the community on the possibility of subreddits. Most people said they wanted them, and I said I'd investigate.
I talked to a couple of people and eventually ended up talking to Tricycle, the developers of this site. They told me about their own proposed solution to the community organization problem, which is this new Discussion section. They said that searching the discussion section by tag was equivalent to a sub-reddit. For example, if you want a sub-reddit on consciousness, the discussion consciousness tag search is an amazing imitation
I told them I wasn't entirely convinced by this and sent some reasons why, but I haven't heard back from them lately and I'm not going keep pursuing this and make a big deal of it unless a large percentage of the people who wanted sub-reddits are unsatisfied.