Hi lwendell,
I don’t know the specifics of the Hawn Bedding mattress you are looking at (type and blend of the latex or thickness of the layers and the type of cover) but assuming that it’s latex then both of these would be good quality choices with no obvious weak links but they are different types of mattresses. The mattress at Hawn Bedding is a sleeping system that is probably a thinner latex mattress but includes an “active” box spring which will be a significant part of how the mattress feels and performs. As you mentioned it is also two sided. The advantage here is that you can test the set in person for PPP (Posture and alignment, Pressure relief, and Personal preferences).
The SleepEz mattress is a different design that you can’t test in person ahead of time so there is a little more risk but it also uses layer combinations that can be customized and can also be re-arranged or exchanged after a purchase to fine tune the mattress to your specific needs and preferences. They can also be replaced without having to replace the entire mattress if your needs or preferences change or if one layers softens before the others.
Both of these use good quality materials that have no obvious “weak link” in the mattress. If you are choosing between these then you would be choosing between “good and good” and your final choice (see post #2 here) would depend on all the objective, subjective, and intangible parts of your personal value equation that were most important to you. Both of these could make very good choices IMO.
Assuming all the other factors that contribute to durability are equal … then any two sided mattress will last longer than the equivalent one sided mattress … even with a material as durable as latex. There is more about the pros and cons of one sided vs two sided mattresses in posts #2 and #3 here.
If the type of latex and the ILD of the latex was the same then in practical terms yes. While a single layer may have a slight advantage over multiple layers in “theoretical” terms … It wouldn’t really translate into much of a measurable difference if any in real life if both are enclosed in a suitable cover. For example … two 3" layers of latex in the same ILD would last about the same length of time in practical terms as the same type and blend of latex in the same ILD in a 6" layer. Softer latex (or any material) will be less durable than a firmer version of the same material. There is more about the many factors that affect the relative durability and the useful life of a mattress in post #4 here.
Phoenix