Hi Samspade,
Post #1 here can help cut through all the thousands of pages of information here and focus on the basic information, steps, and guidelines that are most important.
If you find yourself reaching “paralysis by analysis” you are probably getting overinvolved with “theory” when your body and local testing will tell you much of what you need to know.
Latex is a very durable material so having a two sided mattress is less important than it would be with less durable materials but any material will last longer in a two sided construction yes as long as it is regularly flipped and rotated.
The tradeoff for a two sided mattress is that there is less “room” to design a mattress that has progressive firmness because if you have more than about 3" or so of soft materials on the bottom of the mattress then it can be risky for support/alignment. The middle layer in a two sided mattress needs to be firm enough to be a suitable support layer and to some degree compensate for the softer layer underneath it but with a support layer on the bottom you have more flexibility to fine tune the top and middle layers to your liking without compromising support. A component mattress also has the advantage of being able to replace just a single layer (usually the top layer softens first) without having to replace the entire mattress so this also has a durability or longevity benefit as well.
In the end it’s a preference issue and if a two sided mattress is perfect your specific needs and preferences in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) and is a similar or even slightly higher cost than a one sided mattress with the same amount of latex and a similar quality cover then the additional design flexibility of a one sided mattress may have little benefit to you and the two sided mattress would be better “value” for most people.
On the other hand if the design flexibility of a one sided mattress provides better PPP or the ability to fine tune a component mattress or replace just a single layer as necessary is more attractive to you then this may be a better match for your personal value equation.
Every benefit has a corresponding tradeoff and once you know both sides of the tradeoff and have tested both mattresses then you are in the best possible position to decide which one is most valuable to you based on the criteria that are most important to you.
Have you tested them both … and did you prefer one over the other?
Until you actually try them out your process will be based more on “theory” than actual experience and you may find it will become more and more impossible to predict which you will end up sleeping better on.
Phoenix