Jim,
We also had the Samsung RF18 installed in June.  Our first trip was a short one two weekends ago.  Before we headed out I had the coach stationary in my workplace parking lot for nine hours.  Of which six hours were in 90+ degree heat running on the 2000 watt inverter.  I have four house 6V wet cell batteries.  The only problem we had was the ice cream was too hard to scoop!  

  The LED lights are super bright and we had a full bucket of ice the next morning.
We adjusted the freezer up a few degrees and all was fine.  One of the best decisions we have made.
My brother-in-law is running a Norcold 1200 and he cannot maintain proper temperature in his freezer nor fridge.  It is a fairly new unit.
Best of luck!