Hi jege41,
In this case your “better judgement” may not be completely accurate because there are several factors involved in durability and longevity vs “failure” of a material.
If you were to talk with a cross section of mattress manufacturers who have experience with every type of latex over the long term or talk with the manufacturers of the latex itself, their experience would give you some different insights and you would find some different opinions based on their own long term experience.
In the lower ILD’s and in an apples to apples (same ILD) comparison … blended talalay will be more durable than all natural talalay in the lower ILD’s (see post #2 here). In the lower ILD’s the natural elasticity of the talalay and its thinner cell walls along with the greater inconsistency of natural latex works against it and it ill be less durable than a blend. This will start to even out as the ILD’s get higher.
With Dunlop it’s the other way around because of its higher density, greater firmness in most cases, and the properties of natural latex itself (see post #2 here for a comparison between natural latex and synthetic latex). While overall natural latex has more desirable qualities than SBR (synthetic) latex … the synthetic does have some advantages over natural in some areas that can add to its properties so it’s not quite as black and white as “natural is better”. Even good synthetic rubber is a higher quality material than most polyfoam and not the same at all. Tires are the same and tires that include synthetic rubber will last longer than natural rubber tires although natural rubber can add to higher performance.
Softness itself is also a durability factor and softer materials (which are much more common with blended Talalay) will be less durable than firmer materials of the same type.
Phoenix