I was using Spam Hammer but have just replaced it with this mod due to the fact that it has more options that the SH free version. I like being able to post the blocked attempts in a thread in my Admin section to show the moderators that we are being successful in blocking spammers.
But I doubt that this will be getting much work as Spam Hammer has not been needed to block any bots since I installed the hack to block spam bots by hostname or user agent from registering. But the way I look at things is better safe than sorry!