I read an article a few days ago about setting up the Ricoh GXR as a Leica M Monochrom camera replacement and, because it was a dull, gloomy day today when I went for a walk I decided to try out the settings and shoot in black & white. In reality, setting the camera up to act like a Leica Monochrom was as simple as selecting high contrast black & white jpeg and switching to manual exposure mode but I actually set the camera to also produce RAW files and used aperture priority mode instead.
When I imported the pictures into Lightroom I turned on a preset which kept the images as black & white so I could assess them as black & white (the fact that there were raw images meant that Lightroom would automatically build new preview images in colour). Although the images are not as good technically as a Leica would produce (or as good photographically as a good photographer would produce) it was still an interesting exercise to look at images in black & white for a change.
All post production was carried out in Lightroom CC.