For those of you that don't get Andy Dunn's weekly webmaster newsletter, he recently had his annual issue where he talks about the issue of recurring versus per sign up. "Pay Site Math" is what he calls it.
Here are his latest graphs:
http://trix.sexswap.com/paysitemath.html
Here is the issue where he starts talking about it:
http://trix.sexswap.com/swap231.htm
Here is his conclusion:
You may notice that if you put the two trangles together on the ends of blue graph, it would equal the front of the red graph. What's this all mean? It means you cash out your chips earliest in PER SIGN UP systems and there is a BILLING LAG in recurring systems. This is why I have ALWAYS preferred per sign up. If you like getting cash after you stop working, then you may prefer recurring percentage.
Andy is a madman and he also gives his opinion on why content isn't important, more formulas than you need, Bang Bus type sites, and all sorts of other random opinions. Agree or disagree, it's worth reading, as is most all of Andy's stuff.