I'm going to be testing a module that emails commenters when there has been a reply.
My trial enabling node comments went pretty well, I did have to handle the inevitable comment spam but there was nothing outrageous - only about one bogus comment a day. With comments being published only after approval they're extremely easy to spot as well, since typically the spammer will post the same comment twice or more once they realize "hey, it hasn't appeared on the page yet!"
So because of comments are functioning well I've just enabled some new features for my blog - namely, you can now leave your name & homepage when you leave a comment, although due to homepage spamming I've disabled all homepage links in the site theme until I find a better solution. As well, you'll notice the new rating widget (thanks to VotingAPI and Fivestar) on every node - feel free to leave any feedback or ratings on any of the blog or tutorial posts. Thanks!
I've always been hesitant to enable comments on my posts due to spambot activity, but I'm hoping Drupal is a bit better than Joomla at fending spammers off... I'm going to enable (moderated) comments for a week and see how it goes. Feel free to leave a comment on any of my articles!