Hi Mellillo,
I would make sure that you can find out the type and density of all the foam layers in any mattress you are considering because it’s the only reliable way to know about the quality and durability of a mattress. A warranty has little to nothing to do with the durability or useful life of a mattress because it only covers defects and not the gradual (or more rapid in the case of lower quality materials) loss of comfort and support that come from foam softening (either with or without visible impressions) that is the biggest reason that people need to replace their mattress. Warranties are more about marketing than they are about the useful life of a mattress (see post #174 here).
If the salesperson you are dealing with either can’t or won’t tell you the density of all the foam layers then I would avoid the mattress completely and I would avoid the major brands anyway unless you can confirm the quality of the materials inside them (see the guidelines here).
The choice of materials is a personal preference and not a “better/worse” choice so whoever is telling you this is “selling you” not “educating” you. Every material has higher quality and more durable versions and lower quality and less durable versions and regardless of the material that you tend to prefer it’s always important to make sure that the specific version of that material in a mattress you are considering is durable enough for your body type. There is more about how memory foam or gel memory foam compares to latex in post #2 here.
There is more about the most important parts of the “value” of a mattress purchase in post #13 here that can help you make more meaningful comparisons between mattresses but it comes down to testing for suitability (PPP), checking for the durability of the materials, and then comparing your finalists for “value” based on all the other parts of your personal value equation that are most important to you (including the price of course and the options you have available after a purchase if you aren’t confident about your choice or it doesn’t turn out as well as you hoped for).
If you are in reasonable driving distance of Pelham then a trip to Royal Bedding would be well worthwhile. You can see some comments about them in the Birmingham list and here and here as well.
Phoenix