Hi gapoochi,
The first place I would start is post #1 here which has all the basic information, steps, and guidelines you will need to make the best possible choice. It will also help you eliminate the worse choices such as chain stores, major brands like Sealy, or any manufacturer or retailer where you aren’t able to find out any meaningful information about the quality of what is inside your mattress.
The description you posted of the Kodiak doesn’t have any of the quality details of the mattress and knowing the quality of the materials (not just the type of materials) is essential for making meaningful quality and value comparisons between mattresses. You can see some more detailed comments about the Kodiak that includes the foam quality in post #3 and #4 here. As you can see this would also not be in the best value range and it uses mid quality materials (with a higher budget price)
Of course Sealy won’t give you any information at all about what is in their mattresses and in these cases it’s always safe to assume that it’s lower quality yet. There may be better or “less risky” options available to you than either of the choices you are considering.
A warranty has nothing to do with the usable lifetime of a mattress and when you see a 25 year warranty it’s about marketing not how long the mattress will last you. As you can see in post #174 here which talks about warranties … foam softening and the loss of comfort and support that goes with it (and is the reason that most people need to replace a mattress) is not covered by warranty. In some cases this can happen very early in the life of a mattress (depending on the suitability of your choice, the body type of the person, and on the quality of the materials) and then you are stuck with a useless mattress with a 25 year warranty and no options to exchange it for another one.
A comfort guarantee is only as good as the options you have for exchange and in many stores that promote Sealy mattresses … there isn’t a single mattress that I would consider either as a purchase or as an exchange. In the mattress shopping guidelines … #10 is to buy a mattress with very careful and objective testing as if your first choice is your final choice. A comfort guarantee can be a useful backup plan but in many cases all the initial purchase does is lock you in to exchanging for another lower value mattress.
It seems like you have already found the forum list for your area but if you me know your city or zip I’d be happy to make sure you know about the better options in your area.
Phoenix