To moderate or not?

One other thing that I guess might annoy people is that I moderate comments, mostly to keep spam out. Akismet picks up tons of spam, but some comments still get through, and if anything this is increasing.

Justin uses a very simple Turing test to check if the respondent is human, and it seems unikely that the spammers are going to keep track of the required answer to that test for every blog, so I’d imagine it’s quite successful.

So, would I be better off switching moderation off and a Turing test on?