Hi ejp,
I believe you’re referencing some information provided in this post. In general, softer latex will be less durable than firmer latex, especially when in the uppermost comfort layers (where ultra plush latex is usually placed), whether it is blended or natural Talalay. There can be a slight difference in durability in these very plush types of latex between blended and natural (the blended can be a bit more durable), but I would consider both types of materials to be high quality. It is true that there are some manufacturers who eschew 14-15 ILD Talalay, regardless of blend, and prefer 19 ILD, for overall durability concerns, relatively speaking.
There’s quite a bit more involved to foam durability than the ILD. I discuss this in more detail in this post.
Phoenix