The ability to update a preset as opposed to just creating a new one.
I am using an artnet dmx controller to assign presets to certain cues with my lighting and occasionally i need to tweak a preset. Since the DMX is sending a specific preset number i currently have to load the preset, adjust it, create a new one, move it into the place of the old one and delete the old one.
Is that clear? Hopefully I am explaining it well enough.
Perhaps load a preset, hit an 'edit' button to put it into edit mode, and when changes are made hit save. This would also be useful in moving a setup from place to place.