Perhaps the crux of any discussion about durability and reliability has as much to do with how much folks are willing to pay as it does about the material being used. I think it is certainly possible to build an RV that will last lifetimes and the roofs on high end motorhomes and buses to a long ways in meeting that need as do the roofs on high-end fifth wheels.
The same is true to wall construction, etc. For the manufacturers it is a juggling act and they have to be able to sell what they build framed against the RV industry statistic that fully 50% of first time builders keep their rig less then two years and use it less than 20 days out of the year.
In the end you still get what you pay for.
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SC