Hi insidescoop,
There are occasional reports of delamination on this forum, but they're infrequent and wouldn't support an argument that there's any kind of general manufacturing problem. And while delamination can occasionally be traced back to a manufacturing problem, it's most commonly due to water intrusion.
As for holding tanks freezing, if you are in ambient temps below the low 20s (F), it's hard to keep the underbelly temps above freezing, even if you run the furnace with a thermostat setting of 72. The YETI package, if the trailer you're buying is so equipped, includes tank heating pads that will protect tanks from freezing.
If you're going to be in extreme cold weather, and the trailer you buy doesn't have them, you should invest in tank heating pads regardless of what brand of trailer you buy. Of course it's easier to install at the factory than in the field. But it is possible to install them locally.
You should understand that in the RV world, warranties are only for the original purchaser. You will have no warranty coverage. Regardless of whether the issue is minor or major, it's very unlikely you'll get any help from any RV manufacturer, or any RV appliance manufacturer. So take some of the money you save by buying used, and set it aside in case you need repairs.
