Heat is a function of total input power. 2,000 watts of HID or 2,000 watts of LED will in the end product 2,000 watts of heat. The heat advantage of LEDs is when you run multiple chips at lower power thereby turning more watts into usable light than HIDs. Depending on the details of the LED build, 1,200-1,600 watts of LED might be similar to 2,000 watts of HID, or in other terms, 20%-40% less heat. But again, it depends on the specifics of the build; e.g., number of chips, type of chips, how hard they are driven, etc.