I replaced a Works Shock on my K75RT with a Fox Twin Clicker from a K75S. The spec for travel is the same for both bikes, and the ride with the Twin Clicker is virtually the same, if just a tiny bit more plush(probably due to damping adjustments). Rear wheel loading is virtually the same for both models as far as how I ride, so I would expect the spring rates are the same as well.
BMW shows different p/n for different models, but shows similar specs for travel, etc. Different internal damping????