If you really want to make a more capable gradient capability, the most useful addition in terms of raw power/flexibility isn’t changing the color space where interpolation happens, but instead adding some facility for non-linear interpolation on each segment. For instance, allowing arbitrary cubic (or even just quadratic) polynomial segments would give the tool dramatically more flexibility for a given number of specified colors, comparable to the difference between polylines vs. Bézier splines for specifying 2D shapes.
@jrus wrote: