Hi Maconi,
I think your comfort and design questions would be more effective as part of a phone call with each manufacturer. there are too many “it depends” in the answers along with too many variables and unknowns to try to use theory as a way to make a choice of ILD or design. There are links to some of the theory in mattress firmness/comfort levels in post #2 here and forum searches will also bring up many much more detailed posts as well but these are only generic and not specific to any individual and in general it’s best to either use your own personal testing to decide on the design and layering that works best for you or if that isn’t possible then more detailed conversations with each manufacturer will give you the best odds of making the best design choice. They know more about their mattresses and designs and which may work best “on average” for different people than anyone else.
I truly doubt that things like an “ILD gap” would have any practical meaning for you unless you have specifically tested the exact design and confirmed that it either was or wasn’t suitable.
All Talalay latex is Oeko-Tex certified and most Dunlop is also certified through Oeko-Tex or other reputable certifying agencies. Neither of them would carry any latex (Dunlop or Talalay) that wasn’t certified. Uncertified latex would actually be very difficult to find in the US or Canada although I imagine it would be possible.
There is no “bad or good” or “general consensus” that I would go by … only a design that in combination with all the layers and components working together is suitable for your specific needs and preferences in terms of PPP and this may vary with each manufacturer depending on the specifics of their mattress. Choosing a design requires either personal testing or more detailed conversations. If you tested a mattress with a 32 support core and you know the type and blend of the latex and the details of the comfort layer and the cover and quilting and it worked well all together for you then this would make a good blueprint. If it was a little off in one way or another then this would also be valuable information to share with a manufacturer. I sleep on a 28 core and 3" of 22 ILD on each side and I’m 6’5" and 195 … although this would be a very risky design for most people and I certainly wouldn’t recommend anyone try it unless they were confident it would work well for them.
My overall impression is that you may be crossing the line into a level of analysis that would have little real life meaning to you and too much information and analysis or trying to reduce a mattress choice down to a formula can lead to just as many poor choices as too little information. You are dealing with two knowledgeable manufacturers and I would work with the experts and take advantage of their knowledge and experience rather than trying to design your own mattress and becoming an expert yourself so you don’t have to learn what they already know.
Once you have talked with them and made your design choice with each manufacturer and are down to final choices between 2 specific mattresses … then you can look at all the options they each offer after a purchase along with all the other parts of your personal value equation that are important to you to decide on which one is the best value for you.
If they are otherwise identical and every layer is exactly the same type and ILD of latex and the covers are the same then the mattresses would be functionally identical. In other words 2 x 3" cores @32 ILD would be functionally the same as a single 6" core at 32 ILD within the tolerances of the type and ILD range of the latex. In theory the two layers would be slightly softer because they would act a little more independently but this would be outside the perception of the large majority of people and the difference would probably be less than the ILD variation of latex anyway. 3 layers gives you more options to re-arrange or exchange layers to fine tune a mattress for those where this is necessary which is the main advantage of the design.
Phoenix