Any Spam Karma Troubles or Complaints?

Those who know me well, know that I’m very picky about my anti-spam plugins. I’m more concerned with the effect an anti-spam plugin has on my readers than I am with how effective it is against spam (so Captcha are completely out of the question). I’ve spent 24 hours using Spam Karma, and it has done a good job. But, before I commit to using it completely, would anyone wish to discuss any troubles or general complaints they have with Spam Karma, either when commenting or administrating the plugin? And, if you had troubles when you were in control, what did you have the overall treatment algorithm set at (or what was causing your trouble)?