Wow, this got out of hand. I have attended one of these events as an angel investor and found it valuable. I'm sad that Paul's question got such a rough response, as I do see a number of other event organizers in the field who do not show integrity, so I think it is appropriate for a startup CEO to try to figure out what is real, and what is a scam.
As for paying to present, I personally would prefer to see entrepreneurs NOT paying, but, that said, I belong to one of the many angel groups that DOES charge (despite my objections). Check out Keiretsu, Investor Circle, and others to see legitimate groups that charge fees.
As an entrepreneur it always is worthwhile trying to network into an organization in order to evaluate its legitimacy. And if you refuse to present when payment is demanded, that's your privilege. Both sides of the equation may mis an opportunity, but FOMO is not a big driver among the angels I know.