We need Preferences so we can decide if we do or do not want a histogram showing. Don’t hard code it so everyone has to have it open.
We need frequency separation so that different tools/adjustments can be made to work only on a tone layer, a color layer, or the typical combined tone and color layer. This is very important for portrait work, landscapes, architecture…etc.
We need S2 first to be a plugin with round trips to LR, Ps, C1P and others use the plugin APIs from Adobe and Phase One. After that, we need S2 to be able to do a round trip to other apps.
On Basic Adjustment we need to be able to hold down the Option key and move the Black or White sliders and get a visual indication of clipping.
On Basic Adjustment we need to be to select or provide a camera profile (ICC or DCP) that is used by the raw converter before any filters/adjustments are added.
We need a LUT manager that will let us save combos of presets and Looks as a LUT, import LUTs into the library, and select and apply LUTs with opacity.