Jim,
I make it a point not to overbalance my trees. I believe that what is called dynamic balance gives the trees more character. Dynamic balance means that one part may well be out of balance but it is weighed by something else being out of balance. Hard to descrobe in words. See this picture: The tree itself may be out of balance. But this is only a part of the overall design. It includes an empty area which is large enough to catch the unbalanced tree. The whole composition should be balanced again, but convey a very strong dynamich impression.
Walter