I ended up getting the Dometic CFX3 35. Last night I plugged it into my Yeti 1000, using the 12DC, and put 12 cans of soda in it. Set the temp to 38. It ran for several hours then it turned it self off, due to low battery voltage. It looks like the older (non x versions) Yetis don't have a 12v regulated output. That is a problem with the Yeti not the Dometic.
I changed the setting on the Dometic so it won't shutdown for low voltage, and restarted my little test. After a while I noticed that the compressor stop running and the Dometic is showing a temp of 38. I check the temp of one of my cans and it was 56, the floor of the cooler is only 40. I was expecting my soda to cool down to somewhere around 38.
Does anyone know where the temperature sensor is located? My thinking is I should move my sodas near the temp sensor, so that they would heat up the sensor and cause the compressor to come on.