It's great to have some basic controls for lighting such as golden hour and studio lighting. But even deeper controls would be helpful, like "lighting from left", "Lighting from right". Most concept artists use some combination of photo elements, 3d and hand painting in Photoshop to arrive at their final concept. The problem with photo elements is they often have the lighting from the wrong direction, and so when you add those elements to your painting they don't match. Would be great to use firefly to edit the lighting in those photo elements to whatever you need.