Hi CummingsSM,
You are certainly looking at some very good quality/value options 
While there is no way to quantify how long any mattress will last for any particular person because there are too many unknowns and variables involved that are unique to each person, if a mattress is well inside a suitable comfort/support range and isn’t close to the edge of being too soft when it is new and meets the minimum quality specs that are suggested in the guidelines here then it would be reasonable to expect a useful lifetime in the range of 7 - 10 years and with higher quality and more durable materials like latex or higher density memory foam or polyfoam (in the comfort layers especially) it would likely be in the higher end of the range or even longer. There is also more about the many variables that can affect durability and the useful life of a mattress in post #4 here.
The “best” place to use slightly lower density and lower cost materials in a lower budget mattress that will have the least effect on durability are in the deeper layers of a mattress that are less subject to the mechanical stresses of compression when you sleep and will have the least effect on the durability of the mattress. If you were in a higher weight range (more than the low 200’s or so where you are) then you would be compressing the deeper layers more and a 1.5 lb support layer would have more effect on durability than it would if you are in a lower weight range and don’t compress the support layer as much. Just as a frame of reference … 1.5 lb polyfoam is an “industry standard” for the support core for most mainstream mattresses including mattresses that are in much higher budget ranges. The upper layers are the place where I would avoid compromising the quality of the materials because they are generally the weakest link of the mattress.
There is also more about some of the differences between a latex/polyfoam hybrid and an all latex mattress like the other two mattresses you are considering in post #2 here but if you are using a 10 year time frame as an expectation and reference point for the useful life of a mattress then the differences will be more about feel and performance than about a significant difference in durability (although there may be some). Beyond 10 years an all latex mattress would have more “bonus time” or even “extended bonus time” than a latex polyfoam hybrid.
I should also mention that if you were to order a king size instead of a queen that you can also “split” the latex comfort layer into two different firmness levels.
There is more about the pros and cons of split layers in post #2 here. While the goal of a split layer design is to make a noticeable difference between each side (more with “support” than with “comfort”) … how much you would notice it would depend on your sensitivity and on the amount of the firmness difference between each side. The solid top layer would smooth out the transition between sides so it wouldn’t suddenly “change” from one side to another and the top layers provide more of the “feel” that you notice when you first lie on a mattress than the deeper layers. It would also depend on which part of your body was sleeping across the boundary because you would notice more of a difference in how much you sink in with the heavier parts of your body such as your hips/pelvis than you would notice with your lighter legs. If you were sleeping exactly on the middle of the mattress with the split along the midline of your body on your back for example with your head and feet straight from the top to the bottom (and not at an angle) you may notice that you were sinking in or “tilting” more on one side of your body than the other but it would be relatively rare for someone to sleep exactly in this position and most people would sleep more at an angle with only part of their body on the “other side” where the firmness difference would be less noticeable.
Phoenix