I like the new addition to the HSL Colour Wheel where you can see the areas that would be affected by changes to Saturation, Luminance or Uniformity of a selected colour range (with everything else in the image shown in greyscale). However, the method of selecting it is non-intuitive (as evidenced in a number of postings on this topic in other threads). Also you cannot make changes to Saturation, Luminance or Uniformity of the colour range while viewing the greyscale & colour range version of the image - as the image reverts to the full colour mode when you are no longer clicking on the colour range handle on the colour wheel.
What I propose is that the greyscale & colour range version of the image should be able to be toggled on / off via a checkbox in the HSL tool palette. In addition, if changes are made to the Saturation, Luminance or Uniformity of the colour range while in greyscale & colour range mode these changes should be visible in the colour range that is visible in the image.