I was getting beat up recently with spammers, I changed my settings to this (1.4) and It has stopped. (knock on wood.) Also, I did not want to have to moderate new users or their posts/ threads, I think that is a turn off on forums IMO.
I have all the span setting active on XF 1.4 and so far not one spammer so as far as I can see this is the way to go. I have it set to manual approval if any are still flagged and then I just check out those. Most times I am finding it is a legitimate member being caught on their user name being flagged