OT: Comparisons of different Bayes Engines, etc.

[Forrest Aldrich]

I'm looking for comparisons and/or reviews of the various Bayes-specific 
anti-spam engines -- Spamassassin, Bogofilter, etc.  Gathering features, 
performance, ability to tune, actual application in the real world 
(commercial), etc.  

If anyone knows of such resources or has performed these, I would 
appreciate hearing.

Thanks.