Hi ehuesman,
You can read about some of the differences between latex/polyfoam hybrids and all latex mattresses in post #2 here.
The closer to the surface a layer is the more effect it will have on durability so different base layers would have less effect on the durability of a mattress than the middle and upper layers … although they will certainly affect the feel and performance of the mattress.
It would at least be a rough guideline that would be helpful as a reference point in any conversations with online manufacturers if you know the layering that worked best for you (layer thicknesses and softness/firmness rating).
If you are in the San Francisco area there are many good latex options available there as well that are listed in post #2 here.
Phoenix