Hi HolisticallyYours,
Yes … this can give you a good sense of different layer combinations although the ticking/quilting fabric will also make a difference. As you say they are good people.
No … a split top doesn’t compromise durability but it does usually require some kind of layer over it (either in the quilting or in the comfort layer) so you won’t feel the split (athough you will of course still feel the different firmness levels on each side).
It can also be surprising to some people that certain layering combinations can accommodate different weights/heights in the same mattress. For example … a middle transition layer can act as more of a support layer for the person with the lighter weight while it can act as more of a comfort layer for the person with a heavier weight. In some cases … people that have very similar body types and sleeping positions may prefer different layering while couples that are very different in body type and sleeping positions sometimes prefer the same layering. Sometimes all the many variables involved converge together and can lead to the same layering for different people … even though it doesn’t seem “logical”. This is part of the reason that personal testing can be much more accurate than designing a mattress based on “specs” which often only cover a few of the many variables involved in what makes a mattress more suitable for a particular person. In other words there is no “formula” where you can plug in specs (either of the person or the mattress) and come up with the “best” mattress although they can help with fitting people into “averages” that many will do well with.
They can alter both the support components (different innersprings or latex) and the comfort components (microcoils or latex) of the mattress so that you can have the best possible combination of both. Was the firm side the one you thought the comfort layer was too thin? There are some counter intuitive processes at work sometimes in a mattress where for example a softer thin top layer can allow you to “go though” it more and feel the firmness of the support layers while a firmer comfort layer can isolate you more from the support components and feel softer. Thickness and softness of the comfort layers and how much they “isolate” you from the firmness of the support layers (or in some cases how much the qualities of the support layers “contribute” to the comfort layers) are all part of creating the balance between pressure relief and support/alignment. The “critical zone” or “comfort zone” of a mattress (the depth of the pressure relieving cradle that you need) may be partly formed by the upper layers and partly formed by the softer part of the support layers below it so where the “boundary” between the layers may be can be misleading.
The choice between a latex support system and an innerspring support system is really a matter of preference. One is not necessarily “better” than the other. Innersprings have a more linear response (which can be changed with different spring designs) while the response curve of latex is more bananna shaped and innersprings also have a higher resilience (they return more energy without absorbing it) than latex. In addition to this some innersprings have variable spring rates (similar in a way to say a 6" firm layer of latex with a softer 1" or 2" layer on top which is then used as the base for the comfort layers above it) which acts differently again and there are many other variables between the two. Some people may just do better with or prefer one over the other and each type of response may work better for some people.
Some people that can’t make any combination of latex layering work for some reason may do well with latex over an innerspring for example while others that don’t seem to “match” any type of innerspring may do well with an all latex mattress. I do think it’s true that those who prefer all latex would probably not go back to an innerspring but there are some who just don’t do as well with all latex.
Just to be clear … I don’t make recommendations but just provide guidelines that can be used as a reference point for working with a manufacturer or for local testing. There are just too many variables between body types, sleeping positions, preferences, and how all the specific components of a mattress work together (besides just the ILD of the latex) to make any kind of meaningful recommendations based on any formula or what I call “theory at a distance”. It would generally take me several hours of much more detailed conversations that try to take into account many factors to try to design a mattress for someone based on specs and even then the ideal design as often as not wouldn’t be available anyway and in some cases individual preferences and details that hadn’t been considered could lead to different choices once they’d slept on the mattress anyway. Theory is an approximation based on averages at best.
The more specific recommendations I leave for discussions between manufacturers or retailers and their customers because they have much more detailed knowledge of the finer details of all the materials and components in their mattresses and perhaps more important, what they have available to choose from (they usually have a set of standard layers and components that they use). They also have a customer base that they can use as a reference point for the specific mattresses, materials, and components that they use.
The more specific “suggestions” I do make are usually limited to situations where there is a specific reference point of a complete mattress and a single layer needs to be changed or symptoms need to be resolved based on a more detailed description of the “symptoms” involved or on various choices of toppers that may need to be used for fine tuning. Without this reference point of a specific mattress that someone has tested or slept on that produces certain “symptoms” then I limit the information I provide to explanations about how each different layering or combination may affect certain people so that they have a better idea of all the “moving parts” that are involved. For example … there are many manufacturers that don’t even offer 19 ILD in latex because they believe it is too soft and their softest “standard” materials may be in the range of 24. Most of these could probably special order 19 ILD (they certainly have access to it) if necessary but they tend to design around slightly firmer comfort layers.
I would trust the information BE or any of their retailers give you. They (and most of their retailers) are among the most knowledgeable and open manufacturers in the country. There are many instances where the use of firmer latex may be appropriate either by itself or as part of layering arrangement that involved “dominating layers” (firmer layers over softer layers or innersprings). While I personally and I think most other people would have trouble with a latex comfort layer that was all 38 ILD (and didn’t have other layers or components as part of the comfort layers), there are some who wouldn’t have it any other way. Personal experience and trusting your body over any specs is always the key.
I don’t know for sure but I believe their soft latex is @ 25 ILD, their firm topper is @ 37 ILD, and their base latex layers are @38 ILD. the firm topper would be softer on an innerspring than on their firm latex base layer (which is the firmest mattress they have).
Different combinations of materials and components … and sometimes what seems like minor changes … can certainly make big differences in the feel and performance of a mattress. When someone is testing mattresses in person … I would tend to completely ignore ILD information and go by what I was feeling. A focus on specs can get in the way of accurate testing IMO when you are lying on mattresses. If they are a curiosity then I would first choose the “best” mattress and then find the comfort specs out afterwards as a matter of interest. The “comfort specs” are really only important in an online purchase where they have to replace personal experience and even then the final test is when you sleep on the mattress.
They use Radium as far as I know.
This article along with post #6 here and post #2 here and post #6 here may help you choose between them.
Again when you are testing locally …I would ignore ILD’s and only find out after you had decided which mattress worked best for you if the ILD’s were a matter of curiosity.
PLB uses a fire barrier which uses Viscose (Rayon made from wood fibers) and Silica which are both safe materials IMO and either this or wool would be my choice of fire barrier because they don’t use chemicals. You can see more about fire barriers at the end of this article and post #2 here.
Pure Latex Bliss has two separate lines of all Talalay latex mattresses. Their natural line uses blended Talalay. Their “all natural” line uses 100% natural talalay. The specs you listed are from their previous blended Talalay line before the recent change which removed the bottom 1" layer and added it to the second layer from the top in all the models except in the Pamper where it was added to the top layer and which also replaced the blended Talalay top layer with Active Fusion Fast Response Talalay (which used to be called Celsion and is called Talalay GL fast response by Latex International which makes their Talalay latex). Hows that for some confusing terminology? 
You could use this as a reference point in your discussions with a manufacturer yes (along with all the other things that would help them to help you make a good choice) to let them know that this layering was “perfect” (assuming you had tested for both alignment and pressure relief on it) but since a manufacturer may not have the same thickness and ILD’s of layers available or the same cover or the same fire barrier or even the same latex supplier (there would be some differences between suppliers) … they may have to “translate” these specs into a combination they have available and the closest “match” may be an approximation. It would be helpful to them (and you) though as a guideline.
In looking on the Oeko-Tex site … Milliken is listed (who makes the Paladin fire barrier) listed but only for labels. I also found Sateri listed (which makes Visil which is also a cellulosic/silica inherent fabric) but only for their fibers. Spaldin uses Visil and their entire mattress is Oeko-Tex certified. Either way I would consider both of them safe.
Hope this helps … and I would strongly urge you to focus less on specs with local testing (except as a curiosity) which can be much more complex than you may realize and can easily lead to “paralysis by analysis”.
Phoenix