Hi SleepySuzan,
I would be very cautions about using reviews or even any more “absolute” suggestions with a grain of salt because every category of mattresses has a very wide range of designs and quality that make it difficult to make meaningful comparisons between mattresses even if they are in the same general “category”. For every “expert” who tells you one thing you will find another who tells you the opposite. I usually find that it’s always best to make your own assessments and think in terms of “pros and cons” rather than “better or worse” when it comes to preference choices (and the type of materials you like best is really a preference). You can read more about reviews in post #13 here.
Warranties are mostly about marketing rather than protecting the consumer. They all have fairly restrictive exclusions (to different degrees) and the biggest reason that someone will need to replace a mattress is either because their needs and preferences have changed over time or because their mattress has lost its original comfort and support through the softening or breakdown of the materials and neither of these are covered by a warranty. You can read more about warranties in post #174 here.
In most cases … larger manufacturers use warranties as a way to avoid replacing a mattress (it protects the manufacturer more than the consumer) while smaller manufacturers that are more directly responsive to consumers use their warranties as a guideline and will use “best judgement” on a case by case basis to decide what is reasonable regardless of the “technicalities” of the warranty. Many are “in between” these two ends of the spectrum.
From your earlier post as well …
This is also a matter of preference of course and even memory foam mattresses fall in a wide range in the “motion restriction” vs. “motion friendly” scale although as a rule they are less resilient and “motion friendly” than other types of foam. You can read more about this in post #2 here.
Phoenix