One of the weaknesses of this is how, at least on some subs, mods are able to censor discussion largely unnoticed, without being held accountable to the community. See r/declineintocensorship, r/watchredditdie, and r/yallcantbehave for several examples of egotistical mods overextending their role with no real benefit to the community.
I can't help but think that there's a way to hold mods more accountable to their communities. For example, if the modded comment wasn't spam, it could say "this post was removed for breaking rule x which states y. Click here to see the comment," with the mod's username attached.
I would also like to see statistics on removed posts, where a subreddit gets some sort of penalty for censoring too much, such as not appearing on /r/all, or becoming downweighted in some way.