Hi Ms. Natural,
I would keep in mind that the blended Talalay is tested to the same standards for harmful substances and offgassing as the 100% natural Talalay (OekoTex standard 100). It would be very unusual that someone … chemically sensitive or otherwise … had a reaction to either one (even people with MCS usually do very well with blended latex).
This isn’t necessarily the case. Both Dunlop and Talalay can either use blended rubber (a combination of synthetic and natural rubber) or 100% natural rubber (that contains no synthetic rubber at all regardless of which manufacturing method is used). Both methods of manufacturing use other ingredients in their compounding formula except Talalay omits the chemicals used as a gelling agent with Dunlop (usually sodium silicofluoride is the primary gelling agent) and uses carbon dioxide in a vacuum chamber instead.
Dunlop latex is a denser material because of how it’s foamed and manufactured so it would be heavier (more latex and less air in the core) but none of the latex manufacturers release their compounding formula so based on volume (the percentage content of natural rubber in a material) I would be very careful before assuming that all 100% natural Dunlop has more latex in it than all 100% natural Talalay because it may not be correct.
The organic latex from Latex Green (which SleepEz also has as an option for those who wish to use it) is the same as the Latex Green 100% natural Dunlop in terms of the way it’s made. The difference is that the rubber for the organic version comes from a certified plantation and the raw latex material and the production of the latex core has an organic certification. You can read more about organic latex in post #6 here. In terms of natural rubber content or performance it would be the same as their 100% natural Dunlop latex.
Dunlop is generally firmer in the same ILD because the compression modulus is higher (it gets firmer faster as you sink into it more deeply). If a specific layer is compressed by 25% of its thickness they would be the same. With less compression the Talalay would be firmer and with more compression the Dunlop would be firmer. Keep in mind that your body is not evenly proportioned and different parts of a mattress will compress different amounts depending on the weight and surface area of a specific part of the body. If you want a firmer mattress then it would depend on whether you are looking for a firmer sleeping surface or firmer support layers. There are different types of firmness/softness (see post #15 here). Re-arranging the latex or a layer exchange can change the firmness levels of both (pressure relief or support) and both types of latex come in a range of firmness levels. Post #7 here may also give you a sense of the difference in how they "feel but your own personal experience is the best way to know for sure which one you prefer.
If you are looking to change the “feel” of your mattress the first step I would take is a conversation with SleepEz so that you can take advantage of their experience in fine tuning their mattresses although I would make sure you have slept on it for several weeks first because the initial break in and adjustment period with a new mattress can change how the mattress feels.
Phoenix