Hi klphoto7,
You can see a picture of the Myrbacka latex that shows the layers in post #3 here.
Unfortunately the Myrbacka and the Tuft & Needle and the Casper are completely different mattresses with different designs and materials so there really isn’t any way to compare them in terms of how they feel or PPP except in very general terms.
The Tuft and Needle uses a 3" comfort layer that is a high performance 2.8 lb polyfoam that would be less resilient or “springy” than latex but more resilient than memory foam (see posts #2 and #6 here). It has a 7" 1.8 lb polyfoam support core.
The Casper has 1.5" of synthetic latex on top of 1.5" of 4 lb memory foam so the surface “feel” would be more resilient like latex but with only a thin latex layer it would also have some of the slow response “feel” of the memory foam underneath it as you sink into it. It also has a 7" 1.8 lb polyfoam support core.
The Myrbacka has what appears to be about 6" of synthetic latex over a 3" 2.2 lb polyfoam support core so it would have more of a “latex” feel and resilience than either of the other two although synthetic Dunlop latex is less resilient than 100% natural Dunlop or Talalay latex.
None of this factors in anything about the relative firmness levels of any of the materials or the mattress as a whole.
None of them have any low quality materials or weak links in their design.
Phoenix