In a recent comment on Shelley Powers’ site Robert Scoble explained one of his reasons for turning comment moderation on his blog, it has nothing to do with comment spam – he said:
I am seeing more and more anonymous comments and I have been tracking their IPs and see that one person is showing up under a variety of different names
Robert, if someone is posting troll comments under multiple names coming from the same ip address – enter that ip address into your WordPress Options -> Discussion -> Comment Moderation field and then comments from that ip will be moderated – all others will get through.
Be transparent about it – say in a post on your blog that you are moderating posts from that ip because of abuse. People will row in behind you on that.
Moderating all comments seems like taking the lazy way out.