Hi fdb,
This would be an even smaller change than your previous post but if you could feel it at all … in “theory” it would make the mattress a little firmer.
Softness and firmness depends on the type of softness you mean (see post #15 here) and is also subjective and relative to each person’s unique perceptions. What feels soft for some people will feel firm to others. Your own testing or experience is the best way to assess whether a mattress feels soft or firm to you. I think though that for many people this would be considered to be relatively soft.
Changing a layer to one that is a higher ILD would make the mattress firmer which many people “translate” as more supportive. Don’t forget though that how “evenly” supportive a mattress is and how well it keeps you in good alignment in all your sleeping positions is more important than how “firmly” supportive a mattress is. The only way to know which one of the two designs would keep you in best alignment in all your sleeping positions would be to compare both of them in side by side testing although the difference is so small that you may not notice much if any difference at all.
This depends on the rest of the layering and what you are comparing either one to. There are so many unknowns, variables, and preferences involved when you are comparing such small differences that there is no no formula or “theory at a distance” that can predict which one would be a better “match” for you in terms of PPP (see mattress firmness/comfort levels in post #2 here). In “theory” higher ILD’s are firmer than lower ILD’s so 3" of 28 ILD over 3" of 32 ILD would be firmer than 6" of 28 ILD and softer than 6" of 32 ILD if all the layers are in the same position in the mattress and otherwise have the same layers above and below them but how much of this someone may actually “feel” either in terms of pressure relief or alignment is impossible to predict.
Phoenix