Hi JW,
Congratulations on your new mattress
You certainly made a great quality/value choice and I’m looking forward to your comments and feedback once you’ve received it and have had the chance to sleep on it for a bit.
The depth of a warranty exclusion can vary depending on the materials and components in a mattress’ design. With mattresses that have a cover that is quilted with either natural or synthetic fibers or with quilting foam the most common warranty exclusions are in the range of 1.5" - 2" because the exclusion needs to take into account that quilting materials can also compress to some degree over time…
Mattresses that don’t have a quilted cover and that use high quality materials in the top layer such as latex or good quality memory foam usually have a warranty exclusion that is .75" - 1".
While a warranty is important to guard against manufacturing defects in the materials or components inside a mattress that can happen on rare occasions … I would also keep in mind that mattress warranties only cover manufacturing defects and they don’t cover the gradual (or more rapid in the case of lower quality comfort layers) loss of comfort and support that comes from foam softening that is the main reason that most people will need to replace their mattress. In other words warranties have little to do with the durability or useful life of a mattress or how long it may be until you will need to buy a new one. If there is an actual defect in the materials it will usually show up early in the life of the mattress but knowing the quality and durability of the materials in your mattress is always a much more reliable way to assess the durability and useful life of a mattress than the length of a warranty. There is more about mattress warranties in post #174 here.
While there is no way to quantify how long any mattress will last for a specific person or predict exactly when you will decide to replace it because it is no longer suitable or comfortable for you (because this is the only real measure of durability or the useful life of a mattress that really matters) because there are too many unknowns and variables involved that are unique to each person … if a mattress is well inside a suitable comfort/support range and isn’t close to the edge of being too soft when it is new (see post #2 here) and you have confirmed that it meets the minimum quality/durability specs that are suggested in the guidelines here (which your mattress exceeds) then it would be reasonable to expect a useful lifetime in the range of 7 - 10 years and with higher quality and more durable materials like latex or higher density memory foam or polyfoam (in the comfort layers especially) it would likely be in the higher end of the range or even longer and the chances that you would have additional “bonus time” would be higher as well.
Phoenix