At some point I saw some crazy study on perception that claimed that in a blind beer tasting people preferred a batch that was laced with a touch of balsamic vinegar, but when told that one of the batches had vinegar in it they preferred the plain batch. (I think that was the way it went)
I have been considering using balsamic vinegar to my batch of Flanders Red if it isnít acetic enough for my tastes.
Iíd suggest just trying it added directly to the glass, that way you can add it slowly until you hit the flavor profile you want. That would also remove the risk of having 1 gallon of unpleasant beer if you end up not liking it.
Good luck, and of course post your results.