Almost all maker of refrigeration unit use the same compressor by Danfoss. The two most common model of compressor are the DB35 (smaller) and BD50 (bigger).
In my case I used the smaller BD35 air cooled compressor and it worked very well during our winter in the Bahamas. I did not take measurements of the running time vs stand-by time but it seemed very reasonable AND all that time the compressor was on its lowest speed (speed are adjustable by adding/removing a resistor). But my icebox was a bit modified by adding insulation all around (spray can) and also raising the bottom a couple of inch, because this is the area with the worst insulation from the factory, and because it is just too deep to reach anyway. Volume went from 8 cu. feet. to about 6 cu. feet. I recommend both modifications, or at least the first as it is fairly quick to do.
Also, I used the evaporator which is built to form a box with a little door. This worked perfectly and stuff stayed frozen in this compartment.
The compressor was put on a bracket in the aft compartment (over the diesel tank) with a hot air exhaust to the cockpit so as to not overheat the compartment. Not sure how much this vent helped versus just letting natural air circulation...