Allow more and more varied posts to survive without karma bombing. My favorite other idea is charge downvoters one karma point for each downvote as is done on stackexchange.

Personally, I fall on the 'all of the above(except idea A)' side of the fence. I primarily use LessWrong for the Main board, as it is an excellent source of well-edited, well-considered articles, containing interesting or useful ideas. I want the remainder of the site to thrive because if there is not a large, active userbase and new users being attracted, then I would expect to see the types of content I want to see become less frequent. All of these ideas seem like good things to do, keeping in mind that if these do not actually support the goal of making good Main articles more frequent, then they are not good things, and it seems possible that some of these could backfire.