Hi hshanka,
I don’t know the specifics of why they have the warranty they do or whether their warranty covers all their mattresses or just most of them so for this you would need to talk with Brooklyn Bedding directly.
I typically pay much less attention to warranties than I do to the quality of materials in a mattress (see this post) because warranties only cover defects and foam softening or the gradual breakdown or change in feel and performance in other materials and the gradual loss of comfort and support that goes with it is not a considered to be a defect even though it is the main reason a mattress needs to be replaced. A warranty is really only as good as a manufacturer’s responsiveness to customer service issues and which way they tend to “lean” in the grey areas of warranty coverage when they have unhappy customers. Smaller manufacturers tend to work towards resolving issues in ways that are more personal and focused on customer satisfaction than most larger manufacturers who tend to be more focused on finding reasons to deny warranty claims.
Select Foam has a series of rotating sales that don’t end … just change. If you do decide to go in this direction … it may be worth talking with them as well about replacing one “sale” version with another.
Phoenix