I think warranties tend to get more attention than they deserve. A long warranty doesn’t necessarily mean a mattress will stay comfortable for that long. Most warranties cover manufacturing defects, not the gradual softening or loss of support that causes people to replace a mattress.
For me, the bigger question is the quality of the materials and whether the manufacturer is transparent about what’s inside the mattress. That’s usually a much better indicator of durability than a 10- or 20-year warranty. This is the reason why the Mattress UnderGround exists, to educate on quality materials, foams, fibers and all other aspects of what goes into crafting a bed and bedroom set-up.
The custom options and local manufacturing you mentioned would probably influence my decision more than the warranty itself.
For what it’s worth, here is a conversation I had a while back with someone who worked as a warranty inspector for one of the legacy brands. It may not be representative of every company or every warranty claim, but it does offer some interesting perspective. After reading it, I’d ask myself whether I’d really want to rely on the warranty process in the first place.
Maverick