Many higher quality manufactures have changed to fiberglass sidewalls, with foam insulation 1.5" thick in a sandwich, vacuum bonded together. This proves to be very reliable, air tight, good insulation, and durable in RV use, where it is bouncing down the road constantly.
This unit looks like it has a 1.5" stick wood frame, and typically would have thin fiberglass insulation, with aluminum siding, and whatever they want on the interior, many times it is thin wood paneling. Because the aluminum is not glued to the outside and the inside panels are not glued (typically) to the upright panels, they are not nearly as rigid. And 1.5" fiberglass is not nearly the insulation value of 1.5" of foam. Fiberglass allows air to flow in and out of the walls, so on a windy night, it can have double the air changes with outside air, compared to other construction.
So if your plan is camping in good weather, it will work great. Camping in humid or raining weather that might get windy? Not so great, you would need to run the furnace more, or run the A/C a lot.
Durability? I have had no sidewall problems in 50,000 miles with my Fleetwood Bounder - I bought it in November 96 new. It has fiberglass sidewalls, rubber roof. I did have to re-coat the rubber roof twice.
I know that Airstream all aluminum construction is also great process, with seams that do not leak or separate.
I don't think that this RV will be around in 20 years, just a guess though. Many aluminum sided RV's are worn out by the time they are 20 years old. While a fiberglass sidewall RV might still look like new if it is clean and waxed properly during it's lifetime, and you might not be able to tell that it is 20+ years old.
Good luck,
Fred.
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