I'm using PhotoMechanic for culling and marking images for editing, and then edit them in Nikon NX Studio. It is annoying that Nikon has it's own proprietary way to store the sidecar files, but I'm really interested in a solution for PhotoMechanic to write the ratings to those nksc files.
All I do with PM is look through images I already copied and renamed (with a custom script), give ratings and delete the trash. So, with my new PhotoMechanic subscription now being even more expensive than the entire Adobe Photographer CC suite, I kind of expect some more non-mainstream features to be added. Support for the Nikon first party software metadata format would be a real timesaver for me.