Hi!
Editing own comments is a larger problem: You will need to identify users that made a comment, so an anonymous user will never be to edit his comments, else he would be able to always edit also other peoples comments.
Then this also opens up problems with Spam. If a user contribues a comment to a moderated entry and is approved, if he edits his entry and then adds spam, must his editted version be put into the moderation queue again, or will it be immediately published? if he just corrects a typo, he might be frustrated his comment gets into the moderation queue again. And what if someone other already replied to that comment, and the original authors just edits his comment so that it does not fit the previous reply anymore?
Many conceptual problems here.
Best regards,
Garvin