The high failure rate of RV absorption type fridges has very little to do with what class of RV they are in. How they are installed at the factory is directly related to how well they will cool as many are improperly installed with many RVers complaining about lackluster cooling performance.
It's a crapshoot to how long an RV fridge will last, we do know that the more level an RV fridge is operated over it's lifetime improves overall longevity. Most common issue is a clogged cooling unit and they can be replaced, Amish cooling units tend to be of higher quality.
Many RVers have reported 10 plus years of reliable service from their RV fridges, our Dometic has been rock solid over the last 7 years and cools very well regardless of exterior ambient temps. Guess we just got lucky or maybe whoever installed it was in a good mood that day.