Hi potpot,
I can’t predict what pillow you would need, other than to point out that most lower cervical/upper thoracic issues tend to be pillow related, and you’ll want to make sure that whatever you chose helps to provide a more neutral alignment and maintains that throughout the night. You’ll want to avoid too much flexion or extension, and if you change positions throughout the night (side to back, for example), some people prefer a pillow that is “shapeable”, such as down, natural fibers or shredded latex. I go into a bit more detail about pillows in post #13 here, and you might find that interesting. Loft, support, comfort and temperature regulation are also other factors to consider. There is also a pillow thread here that you may wish to peruse.
Yes, you may notice a difference if overall the layers used are harder. But the edge in an all-latex mattress will never feel like that used in a typical innerspring product.
All of the layers of a mattress work in unison, but changes made closer to the sleeping surface of a mattress will be most noticeable. These layers will each compress to different percentages of their thickness depending on their position on the mattress, the firmness of each layer, the compression modulus of the material, the thickness of each layer, and the compression force that they are exposed to (which depends on the weight of the part of the body in contact with the mattress and the surface area that is bearing that weight which is constantly changing as you sink into the mattress more or change sleep positions). People tend to “feel through” the top layer more, meaning that you will feel the properties of the next layer down to different degrees. Even the softest latex won’t “bottom out” (meaning it has no more ability to compress because the walls of the cell structure are fully compressed on top of each other) if it is on top of another foam layer and will have the ability to compress more yet even though very soft latex will compress to a much larger percentage of its thickness than a firmer layer. Every layer of a mattress affects and is affected by every other layer in the mattress to different degrees. This compression of each layer is what creates the pressure relieving cradle of a mattress in the top layers, which re-distributes weight and pressure on the bony prominences and pressure points of the body, while the resistance to further compression of the deeper layers is what “stops” the heavier parts of the body from sinking down too far and putting the spine and joints out of their natural alignment. The balance between the opposing needs of pressure relief and spinal alignment is the main factor behind all mattress design and theory.
Making changes as you suggested deeper in the mattress will be less noticeable in your initial comfort impressions, and more noticeable in deeper alignment, although a bit of a firmer overall impression will be noticeable. Going from a ‘medium" and “medium-soft” to “medium” and “firm” for the lower layers would tend to be a more common “progressive” design and would tend to provide better overall deep support.
Changing your second layer from a “firm” to a “medium” will have more noticeable results, although I think in your previous comments you thought that this was too soft for you. If you think that the transition from the “soft” upper layer to the “firm” is a bit too abrupt, you could try the soft-medium-medium-firm combination (changing up deeper support and upper layers, which is mixing a few variables at once, which does make it a bit more difficult to pinpoint the reasons for changes in your comfort preference), and I believe you already tried something similar, and you may wish to do the St-Md, 25d, Fd and see how that works. Another option, which I hinted at in my earlier reply, could be to try something along the lines of 25t, 25d, Md, Fd and see if you like the slightly firmer upper layers.
There really are quite a few different combinations, but I wouldn’t be changing things up just for the sake of change. Focus upon what you’re attempting to address (needing better deep support or a desire to change initial comfort) and address only that specific issue, manipulating as few variables as possible so that you may track your reactions logically to the changes you make. And while edge support is important, I wouldn’t rearrange layers to manipulate that variable, as doing so will change the overall comfort of your mattress, and you’d be prioritizing edge-feel over mattress sleeping comfort.
Phoenix