I agree; don't be fooled by the vanity metrics. Properties of a hackathon necessary to evaluate it fairly against others include not only registration counts but: food, quality of hacks, management/organization, venue, events (beside hacking), sponsors, etc.

Those can't be evaluated until it happens, but let's see how it fares.

It's obviously promotion. I'd love to see you in an advertising job. "You may love or may hate our product; we're not in a position to tell you!"

Word is there's gonna be Red Bull girls there :D