your friend has water cooling as an option on his mind. I did just that. Bought two super cold machines but did not hook up water cooling. It works very well without the water cooling. The duty cycle on mine is 25% for a 5 cf refer and about 33% for a 2.5 CF freezer. Way better than my old holdover plate system that was so much of an energy hog that I couldn't run the freezer in the tropics.

Refer efficiency is much about insulation and use. Adding a lot of warm items and opening it a lot really affects power usage.