Hi virtualdj2,
You can see my comments about the Sleep Science Ara mattress in post #2 here.
You can also see my comments about the uncertainty involved in buying a mattress that is shipped compressed from China in post #6 here
You can see my thoughts about buying from Costco in post #4 here.
Warranties certainly don’t indicate the durability or the useful life of a mattress or how long it may be until you will need to buy a new one. In terms of durability … a mattress is only as good as its construction and the quality and durability of the materials inside it. A warranty only covers defects in the mattress (which tend to happen early in the life of a mattress) and they don’t cover the premature loss of comfort and support which is the reason that most people will need to replace a mattress (see post #174 here).
Needless to say, I would put both of the mattresses you mentioned in the “buyer beware” category and they certainly wouldn’t be a choice I would make when there are so many better options available to you.
Phoenix