I just took ours out for a day trip yesterday. Just some soda, water and sandwich stuff, maybe 20% full. I set it for 38* and put the items in it the night before on 120 volt AC. I put it in the Jeep before leaving, noting that being unplugged from 120 AC and pulled into 12 volts DC, it keeps the temp setting in memory. Nice.
I strapped it in and headed out. Yesterdays trip was more extreme offroading out at Truckhaven for the TDS offroad event. It got some fairly rough and extreme angles thrown at it and it never complained once. I could even hear the water and sodas bouncing around inside.
After a very long day and about 50 miles worth of offroading I got home and checked the temp read out. Showing 38*. I decided to leave it in the Jeep overnight to see if there was any issues with starting the next morning. Keep in mind I have a new Sears Platnium battery bought back mid Dec. 08. I went to start the Jeep about 14 hours after parking it and the Jeep started up as normal, no slow cranking or longer then normal cranking.
Since our normal use will be driving during the day and camping overnight, moving the next day, it was comforting to know it doesn't seem to cause any issues running overnight. I am very happy with this unit and as long as it continues to be problem free, it is a great value compared to the other options.
The only "negative" I found is, being a 43 qt. unit (similar to the Engel 45, instead of the 35), it is a little taller then when I was originally looking at the Engel 35. Because of this, I cannot open the lid all the way (only about 45-50*) because it hits the roof. Cherokees are a little shorter floor to roof then a lot of other vehicles, so this may not be a big deal but it is something to consider. Once I build my slide out for the fridge, it won't be a problem.
So far, one very happy customer and would recommend to others. YMMV