I read Paul Graham's "How To Disagree" (http://www.paulgraham.com/disagree.html) and a blog "One a Day" (http://avc.blogs.com/a_vc/2008/03/one-a-day.html).
Would creating a scarcity of number of comments that can be posted a day (say 3 comments a day) make people think twice before commenting and probably reduce DH0 - DH3 type of responses?
Let us assume that X gets n units of utility for every point of karma the community awards.
Let us further assume that the community only awards points of karma for insightful posts/comments. This appears to be a safe assumption.
If X knew that comments/posts were scarce, which under your proposal they would be, then X will attempt to maximize the karma earned from each comment/post by maximizing the insightful nature of each comment/post.
In a way, karma whoring would actually curtail garbage comments/posts, if comments/posts were a scarce resource.