Hi leelaur,
This would depend on the type and quality of the materials in the comfort layers of the mattress. Some materials (such as latex) are much more durable than others. A “typical” innerspring sold by most of the mainstream manufacturers uses lower quality polyfoam in the comfort layers and these are much less durable and don’t last nearly as long as higher quality and more durable materials. This is one of the reasons that it’s so important to know the type and quality of all the materials in any mattress you are considering (see this article).
Surface modifications such as convoluting or sculpting will affect the softness of the sleeping surface and to some degree the airflow as well. There is more about convoluting in post #2 here.
Your own testing or experience (hopefully using the testing guidelines in the tutorial post) is the best way to decide whether any mattress or mattress/topper combination is a good match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences).
I would also make some very careful “value” comparisons with OMI mattresses and toppers because while they are certainly high quality and the ability to test a mattress or a mattress/topper combination in person has some value as well … they are also significantly more costly than other latex mattresses or toppers that use the same material and you may be able to “approximate” the effect of the sculpted latex topper with a solid non sculpted topper that was in a lower ILD and was “enough” to add the additional softness and pressure relief that you need.
Phoenix