Hi Erroneous,
Differences in durability depends on many factors but in an “apples to apples” comparison then based on my research the difference in durability between them is real but in practical terms would be limited to the softer ILD’s which are used in the comfort layers of a mattress (and which are the weak link of most mattresses). How much this would affect any particular person would depend on how tolerant they were to the softening of the upper layers of the mattress and whether this put them over their threshhold of acceptable pressure relief and support.
You have probably read pros and cons article on the site which is here but there are more technical comments about this in post #2 here and more in post #2 here which is the basis for my belief for those who are more technically inclined. While there is no way to quantify durability exactly because there are so many variables (and there is more about the many factors involved in mattress durability in post #2 here) … in essence the lower the ILD you are comparing the more significant the differences would be up to the range that a materials would no longer be considered a comfort layer and used in the upper layers. So in the range of the upper 20’s … the difference wouldn’t be so much. In support cores … it probably wouldn’t make any difference. Once you get down to the low 20’s and high teens or below … then there could be a more significant difference in softening yes.
It would be rare for someone to notice a difference between them in thinner layers of say a few inches but in a complete mattress some people may notice a difference between the two materials.
As you mentioned … both materials are Oeko-Tex Standard 100 class 1 (safe for babies) certified and you can see the testing protocols here.
Latex international doesn’t provide the source of the chemicals used to make their SBR (Styrene Butadiene) but they are typically made from various petrochemical compounds … although this is not the only way to produce the raw materials. I believe that Oeko-Tex is a reliable test and that both materials are safe.
I am not a big fan of the confusing names they use for their 100% natural Talalay (they call it “all natural”) and their blended Talalay (they cal it “natural”). I think that they should be called natural and blended. The blend is about 70% SBR and 30% NR (Natural Rubber).
So the short version is that in an apples to apples comparison (all other factors being equal) … the Blended Talalay would be more consistent, more pressure relieving, more durable in the lower ILD’s, less dense and supportive, and less expensive. The 100% natural would be less consistent, less pressure relieving, less durable in the lower ILD’s, denser and more supportive and more expensive. Both would be equally “safe”.
The choice would really depend on how important having a natural material for either ethical or “green” reasons was for each person and whether the extra price of these natural/green benefits and any decrease in durability was worth having an “all natural” product.
Phoenix