Most manufacturers do not make a soft or firm spring in any one coil-count spring. In example a 660 coil count mattress will have the same spring system throughout all of the firmnesses. The firmness is regulated by the amount of cotton felt, foam, and the quilting pattern. A 3 inch diamond shape quilting pattern will be a firm. An elongated 2 inch wide knife blade shape will be a cushion-firm.
Comfort is very subjective.
It is different for every person. Most back experts recommend that you sleep on the firmest mattress that is comfortable to you. You can buy the same mattress in several different stores with a different cover and a different name on the labels. If they happen to miss one' we'll remove it. The Bed Company guarantees that any defect in your mattress will be only cosmetic in nature and not structural.