I've only been using Affinity for a short while at this point, but I think the addition of a hex input field to the color panel would greatly reduce the number of clicks to, for example, experiment with various color schemes on a design. The number of different color pickers in affinity is a little confusing to me and seems redundant, but I could be missing something. Either way, a hex input on the default color panel would mean that I'd rarely need to use the other color pickers.