Hi infotech,
While Tempurpedic is not the best “value” … to their credit they are very consistent about their foam specs and have among the tightest tolerances in the industry.
The slow recovery that you noticed is normal for memory foam.
With memory foam … ambient temperatures and humidity can also affect its response and some of the other factors mentioned in post #2 here may account for the difference between them.
It’s also possible (although I certainly wouldn’t jump to this conclusion) that your mattress was replaced with a floor model that was already broken in. The manufacturing date is on the law tag so you can see if it’s more than a few months old.
In any case … while anything is possible in “theory” … it’s unlikely that the materials in the two mattresses are any different. Assuming that the model is the same (which you can also check on the law tag) it’s more likely to be other factors than the mattress materials themselves.
Phoenix