Just for a different perspective, the "Stop Forum Spam" works fantastically for me.
I have tried CAPTCHA Image Verification twice in the past 3 or 4 years and both times had to remove it. Too many new users ended up in a "cycle" and couldn't get accepted.
And I gave up on "queueing up" new members for approval first. So, my process now is very simple and it works very well. KISS.
