Another advantage of the small size and lumen density of the XB-D is that it can reduce the physical size of the reflector as can be seen on this page. Using a smaller reflector  lowers the system costs. This is particularly advantageous compared to the arrays that are available in the marketplace. In addition, with discrete LEDs it is much easier to make trade offs in lumens and lumens per watt by simply adding or removing discrete LEDs as necessary.