The calculation is complicated, but it affects both sprung and unsprung weight. Items that pivot generally are allocated 50/50 sprung and unsprung weight, like the RFM or swing arm. If you think of the rear springs, they would be 50/50. It is a more difficult calculation with the Girdraulic, but these figures are usually just a guide for lightening. If you think of the front springbox, it would be 50/50, but the spring would most likely be different. In terms of calculating spring rates there can be a lage plus or minus without much fuss.
David