The advantage of using Photometric light is, when creating shaped light such as down light or wall light, we can see the shape of the light on the photometric light, so we can estimate the direction or the shape result when we render the scene. Also if we have a lot of lights you can see the difference between one light and the other.
One tip, try adding a disable Vray sun to the scene in this tutorial, with the same direction as the direct light. The scene will be more realistic
Have a nice day!