The appliances in RVs hold up about as well as they do in homes. There are a few items which have a less than 10 year lifespan in RVs:
Batteries
Tires
Air Conditioner
Refrigerator
Fresh Water Pump
With the exception of batteries and tires the others may last beyond 10 years with proper maintenance.
On the other hand the drive components in a DP are designed to provide fleet service in truck so you can expect up to 500,000 trouble free miles vs only 300,000 for a gas MH.
If not for my DW I would always buyy used. She only wants new. She wins...