A minor update, but after seeing a ratio of about 1 comment/3,000 page views, I removed the forced preview for leaving comments. The way it was set up was a real pain, even for me to moderate, so hopefully this will encourage a bit more dialog for some posts. If you have Drupal and are trying to figure out how to remove forced preview (it’s not entirely obvious), here’s what you have to do, courtesy Drupal forums:
It looks like comment preferences are edited on a per-content-type basis in Drupal 6.x. For example, if you want to change the settings for comments on blogs, navigate to Administer -> Content Types. On the "Blog Entry" row, click "edit" and scroll down to select "Comment Settings". There you can set preview to optional. It still won't fix having to enter a CAPTCHA for both preview and save, but at least a user can skip the preview.