Hi Csj0952,
I’m sorry you’re still having issues with your low back. It very well be that you don’t prefer the point elasticity of latex when sleeping on your stomach.
As I mentioned in my previous reply, I wouldn’t know that this is the answer for your or not – no one can predict that via an online forum. Only you would be able to tell via your own personal testing. But it may be that you want something less point elastic for your comfort materials, so perhaps looking at something using high-density polyfoam in the comfort layers that are firmer would be a thought.
If you’re considering doing this, then you should reacquaint yourself with the better quality and types of materials to look for when you go out shopping, as outlined here. I would avoid products using lower density polyfoams, as these will soften considerably in a shorter period of time and allow your back to sway in too much, which you’ve complained about. But you’ve also complained about a product with a harder surface comfort as well. Unfortunately, the major brands such as Sealy/Stearns & Foster, Simmons, and Serta all tend to use lower quality and less durable materials in their mattresses than most of their smaller competitors that will tend to soften or break down prematurely relative to the price you pay which is why I would generally suggest avoiding all of them completely (along with the major retailers that focus on them as well) regardless of how they may feel in a showroom along with any mattress where you aren’t able to find out the type and quality/durability of the materials inside it (see the guidelines here along with post #3 here and post #12 here and post #404 here).
As for trying to “match” a certain product, there is more information in post #9 here about the different ways that one mattress can “match” or “approximate” another one. Every layer and component in a mattress (including the cover and any quilting materials) will affect the feel and performance of every other layer and component and the mattress “as a whole” so unless you are able to find another mattress that uses exactly the same type of materials, components, cover and quilting, layer thicknesses, layer firmnesses, and overall design (which would be fairly unlikely) then there really isn’t a reliable way to match one mattress to another one in terms of “comfort”, firmness, and PPP (Posture and alignment, Pressure relief, and your Personal preferences) based on the specifications of the mattresses (even assuming that you can find out all the specifications you would need for both mattresses you are comparing in the first place).
Overall, and especially in your situation, the only reliable way to know for certain if a product might work well for you and match up with your own PPP would be based on your own careful testing or actual sleeping experience.
Phoenix