Hi Bedlookingrant,
The only materials in the Nature’s Embrace Unison are GOLS Certified organic Dunlop latex along with the organic wool quilted cotton cover. There is no polyfoam or other types of foam or lower quality materials in the mattress and there are no weak links in the design.
Zoning means that there are different firmness levels in different sections of the mattress to provide different levels of support for heavier or lighter parts of the body. Typically there is firmer latex under the hips/pelvis which is heavier and softer latex under the shoulders which are lighter and need to sink in more easily to provide better alignment over the course of the night. There is more about zoning in post #11 here.
Proprietary just means that they don’t disclose the specifics of exactly how they zone the mattress or it’s specific internal design (other than the type and blend of the latex which is important to know) so that other manufacturers can’t copy their design.
The Unison mattress is a high quality organic Dunlop latex mattress that would be well worth considering for those that like the feel and performance of 100% natural Dunlop latex.
Phoenix