I replaced a Dometic tstat with a Honeywell and it has worked well except one problem. Even the Honeywell service center could not figure this one out.
When leaving to go south in December I went to turn the furnace on with the MH in the driveway and the thermostat would only show LO. I needed to direct my electric heater on the thermostat until it got up above 35 degrees and then it would work. Found out the indication was that the temp was too low for the tstat to work. I knew it was cold but did not know the Honeywell home thermostat would not work in very cold temps. Once I started the heating process the furnace would kick on and then all was well.
The installation process was very straight forward and should only take minimum time for the average DIY person.