What's the exchange rate of Acebucks to US dollars? My guess is that it's roughly the same as the one for Chuck E. Cheese currency. The economics of this sort of model (which is similar to that of "Free iPod" promotions, if I'm not mistaken) are such that the amount of work required to earn something valuable (like an iPod instead of a gumball) is too much of a hassle for most users.
Similar companies' affiliates also tend to spring all sorts of hidden conditions and charges on users, so that's something Acebucks should avoid like the plague.
Actually, the free iPod sites that are still operating today choose offers such that they would break even or even make a little money if every single user eventually got an iPod. Most users don't get an iPod, so they would make lots of money except massive fraud has a tendency to bankrupt these sites.
Similar companies' affiliates also tend to spring all sorts of hidden conditions and charges on users, so that's something Acebucks should avoid like the plague.