The Triplanar has a multi-weight system for its counter balance, so if you use them right they can be set up to adjust the effective mass of the arm as well.
If you want reduced effective mass, use the weight combination so that the weight(s) are closer to the pivot. If you want greater effective mass, set up the weights so that they are further from the pivot.
If you want reduced effective mass, use the weight combination so that the weight(s) are closer to the pivot. If you want greater effective mass, set up the weights so that they are further from the pivot.