You know, I think I want to amend my previous definition of free will. Forget the equal-value scenario. Where I think free will would really show its presence is when, in the event of two vastly uneven options, one is able to choose the less desirable of the two. However, choosing this less desirable path cannot be rewarding in such a way that its value overcomes the previously more advantageous option (i.e. demonstrating self control is probably a rewarding action in itself). All weights and values must be taken into account (subjectively). But if, at the end of the day, one still chooses the lesser of the two options, it'd be hard to argue that we are mere reward-maximizing (or punishment-minimizing) automatons.
Trouble is, one can never really know the subjective value of certain actions. I mean, if I'm determined to see things through a determinate lens, I'll just say the value of defying determinism is highly rewarding for an individual (and just rewarding enough to overtake the "more desirable" option). So, until we have some objective way to precisely measure subjective values, proper interpretation of such an experiment is impossible.
[On further reflection, I do like the "everything being equal" scenario for showing that free will does not exist. That is, we will be stuck, unable to make a decision, until the noise in the system is great enough to tip the scales in one direction or another. And, of course, this decision would be random (although I hate to use that term!)]