Thanks for all the good discussion. I'm still not clear on the issue mentioned by w8ye repeated below.

Anyway, as you start balancing a prop by your favorite method of removing material from the heavy blade or painting the light blade, you will eventually find that the prop may balance with one side of the hub down but not with this side up?

If the prop is horizontal in the balancer and doesn't move, one should be able to rotate it 180 degr., and it should remain horizontal. If the prop is rotated to vertical and stays, good. If it wants to rotate, there must be some weight difference in the hub. That difference didn't show with the prop horizontal because it is directly above or below the pivot point. The side of the imbalance will be indicated by the direction the prop rotates from vertical. Make sense? Whatever it is, I think it must be too small to worry about. i'm going with Lou W's advice.