Let me suggest that, if you haven't already, you take some time to understand the various ways that programs handle metadata written into proprietary raw files (such as .NEF) as opposed to sidecar files. While sidecar files can be a pain, Adobe, for example, will not write to a proprietary raw file. Similarly, it will ignore embedded metadata in the NEF file if a sidecar also exists. So you might find, as I did, that you have some information (like Photoshop or Lightroom raw settings) in a sidecar file that does not include IPTC or other data you applied with PM into the NEF file itself.
PM gives you lots of flexibility about how to handle raw files, which is fantastic, but your choice will be dictated by how raw files are handled by other programs you use in your workflow.
Kevin