In my opinion when you are shooting in a lake that has a lot of 7 and 8 pound walleye that the Metal Halides allow you to see the fish in a more "real" color and it makes those walleye easier to decipher from the common carp. Sometimes it seems with the HPS, you may be able to see the fish "glow" more, but maybe not see as much detail in a color that helps you to distinguish fish by features other than shape.