The B&W adjustment layer is frequently used with Luminosity blending mode to enhance color images, and serves to fill in for some of the color-based luminosity tools found in Lr's Develop module. Further, the Hue & Saturation adjustment allows targeted selection of hues and ranges to enable saturation adjustments. I'd like to see the capabilities and UI blended.
On the B&W adjustment layer, we get sliders for six major hue families, but we do not have the ability to fine-tune the selection ranges as with Hue & Saturation. On the H/S panel, we don't get to see all of the hue families at once, sometimes making it difficult to track progress and slowing down work as each range must be selected from a menu.
Please add the H/S "color ramps" to to the B&W sliders for more refined control over hue selection ranges.
Please enhance the UI on the H/S adjustment layer so RGBCMY ranges are simultaneously visible, while retaining the precision color ramp controls.
These two panels may end up looking identical except for one being called "Luminosity" (a new panel instead of updating B&W), and one called "Hue/Saturation." This would mimic the functionality in Lr to maintain consistency, but also enable finer control over color and luminosity, especially for conversion to gray scale.