It appears that the methodology for determining website categories is such that many, many sites are blocked which do not meet the category. For instance, a site gets blocked and categorized as "racism", apparently based on the fact that the subject is or has been discussed there. Not because it's genuinely a racist site, like stormfront or something.
I've been using K9, and it does reliably block sites you want it to, but it certainly doesn't block normal mainstream sites because they use the word "racism", or "guns", or "sex", or whatever.
If Contentbarrier could employ the same kind of filtering methodology that K9 does, it would be great. It has many useful features (the free) K9 doesn’t have, one of which is the ability to apply different or no filters to different accounts on the Mac. With K9, it's all accounts or none.
Unless of course I'm missing some preference or something, which is entirely possible. I'm assuming that one method is based on a computer scanning a site for words or references, and the other is based more on human inspection and determination, and a database built on that.
As it stands, I can't justify spending 50 bucks on CB, when K9 is free. But it is nice other than having to spend a lot of time typing your password and exempting lots and lots of sites all the time.