Decreasing brace height moves impact point to the left and increasing it moves impact to the left. Correct?
Decreasing brace height will decrease the dynamic spine of an arrow, but subtilely. In other words, if you have an arrow that's acting slightly too stiff, decreasing the brace height may help. Since the effect is subtile, it could move the point of impact in either direction. However, I would tend to match arrows to the bow rather than vice-versa.
I should add that since this is an equipment question, it should probably be posted on PowWow.