Hi nicoleak,
I would keep in mind that most mattresses will tend to soften or break down from the top down so the the upper comfort layers will usually be the limiting factor in the useful life of a mattress and not so much the deeper support layers.
I don’t know where you read this but there is more about the different types and blends of latex in post #6 here. While latex in general is a more durable material relative to other types of foam … blended Talalay (at least in softer versions) will likely be more durable (in the case of Latex International) or in about the same durability range (in the case of Radium) as the 100% natural made by each manufacturer. Some of the other factors that can affect the durability and useful life of a mattress are in post #4 here.
While there are too many variables and unknowns for me (or anyone) to know which mattress would be a better match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) until you have slept on it (which is the most important part of the “value” of a mattress purchase) … I can tell you that both of them use high quality materials and there are no obvious weak links in either one in terms of quality and durability. Which one is best for you would depend on the parts of your personal value equation that are most important to you but when there isn’t a clear “winner” between two finalists then post #2 here may help you when you are making final choices between “good and good”.
Both SleepEz and Arizona Premium Mattress are members here which means I think highly of both of them and I believe they both compete well with the best in the industry. It would be difficult to make a “mistake” in terms of quality or value if you are making a purchase from either one of them.
Phoenix