Hi Martina,
I read through the previous posts in the thread and they include links to most of the information that I think could help you but I’ll add a couple more here.
I see from your last reply that you are thinking about using “dominating” layers (firmer over softer) and there is a little more about this in post #2 here and post #2 here.
Related to this there are different types of firmness and softness that different people are more or less sensitive to. There is more about this in post #15 here.
Outside of this type of generic information … the combinations you are comparing are too different from each other or to what you have tried and provided feedback about to really make any meaningful comments or try to guess at how they may feel for you except to say that if a top layer is softer it will have more “pressure relieving” softness and if a bottom layer is softer it will have more “support softness” but they are also different thicknesses overall so the post I linked previously about the effect of layer thickness and the thickness of a mattress will also play a role in how each of them may feel for you.
I really don’t know how either of these will feel for you. I would tend to avoid using a 19 ILD layer as a support layer because it’s softer than a typical support layer but once again each person is unique and your actual experience may surprise me. These two combinations are so different that it’s not really possible to guess how they may feel or compare for you except to say that the first one (with two layers) has a firmer top layer than the second one so the surface feel and “pressure relief softness” would be greater. It also has has a softer support layer than the second one but this would also become firmer faster because it’s thinner. They are too different and the differences are too complex to predict how you would feel on either of them or how they may compare for you. A “standard” layering would be 19 over 28 on a two layer mattress or 19 over 28 over 36 on a three layer mattress and once you have tested either of these and described your experience or the “symptoms” you experienced on them then it would be easier to guess at how a new layering that only had one specific change may feel as part of a process that may help with any symptoms you are experiencing on either of them.
In other words, outside of more generic information, I would need a reference point of a specific combination you have tried that is closer to these combinations to be able to compare them to what you have actually tried or be able to guess how a combination that has only a smaller change or changes that are less complex compared to what you have tried may feel or compare for you.
When you are experimenting with different or unusual layering then trial and error and your own feedback on different combinations are one of the most important parts of the process.
Phoenix