So far, the only effect that all the Omega-talk has had on me is to make me honestly suspect that you guys must be into some kind of mind-over-matter quantum woo.

What on Earth gives you that impression?

Omega makes a decision to put the money in the box, or not. In my model of (MWI) reality, that results in a branching - there are now 2 worlds (one with money, one without). The only problem is, I don't know which world I am in. Next, I decide whether to one-box or to two-box. In my model, that results in 4 possible worlds now. Or more precisely, someone who knows neither my decision nor Omega's would count 4 worlds.

But now we are asked to consider some kind of weird quantum correlation between Omega's choice and my own. Omega's choice is an event within my own past light-cone. By the usual physical assumptions, my choice should not have any causal influence on his choice. But I am asked to believe that if I choose to two-box, then he will have chosen not to leave money, whereas if I just believe as Omega wishes me to believe, then my choice will make me rich by reaching back and altering the past (selecting my preferred history?). And you ask "What on Earth gives me the impression that this is quantum woo?"