Akismet Failing - Defensio Or Mollum?

I have been using Akisment for spam blocking here, and on other sites that I run or manage. Plugin/module is available for both Wordpress and for Drupal. It has been a great service for stopping spam on their tracks and saving a lot of my precious time. Lately though, I have seen an increasing number of spam slip through its filtering algorithms.  Since this is happening for all the Wordpress and Drupal sites, it cannot be something due to the sites themselves.

I think it is time to think about the other options.

There is Defensio. It has a Wordpress plugin but no Drupal module as of this date. But it seems to be pretty good, and my friend Mayank seems to be pretty pleased with Defensio.

Then there is Mollum, an endevour by Dries Buytaert (founder of Drupal) and Benjamin Schrauwen. It obviously has a module for Drupal, but does not yet have a plugin for Wordpress.

This is something I need to dig into a bit. Any suggestions are much appreciated.