Well, let's see what the data says. I confess I want the universe to surprise and confound. I want the theories to be wrong, I want reality to be stranger than fiction. That would be awesome!
Or I am wrong, in which case I'll happily pay out[1]. I'm a layman, as if that wasn't obvious, and it will be a much-needed physics lesson. Win-win.
[1] If in Australia, payout will take the form of alcohol credits at an establishment of winner's choosing. Hey, I want to learn from my superiors :) If not, a crisp USD$100 note will be posted to any mailing address in the world, to be supplied.
I want the theories to be wrong too, it's just that I'm a sceptic in this case simply because of the utter awesomness that would be the result.
I will happily spend more than $100 just on delivery if that is required to make a payout in liquor (local Swedish flavors) across the world. Crisp paper is fully acceptable as well :)
Doubt we will ever settle this though... I have painfully little faith in scientific breakthroughs.
That reddit post (and admittedly it is just a reddit post) actually says the opposite: there is no theoretical basis for antimatter not to behave exactly like regular matter in the presence of a gravitational field.
The null hypothesis (and, in the absence of any strong evidence to the contrary, the stronger hypothesis) is that antimatter and matter respond to gravity in exactly the same way.