Hi G671,
It would be due to “all of the above” and much more. All the layers and components in a mattress (including the cover) will affect the feel and performance of every other layer and component and the mattress “as a whole” and layer thicknesses, layer firmnesses, the type and blend of latex, and any of the other specifications of a mattress that are part of its design will all combine together and affect which mattresses are a good “match” for you in terms of PPP (Posture and alignment, Pressure relief, and your Personal preferences) … and which ones aren’t. A mattress that feels “perfect” for one person may be completely unsuitable for someone else to sleep on so there is no “magic” in any particular layer and component because each person is unique and it’s the “sum of all the parts” and how they interact with your body type, sleeping style, and individual preferences that is the reason for your experience.
There is much more to a mattress than just the thickness of the layers so there could be some 6+2+2 mattresses that work well for you and some that don’t and some 3+3+3 mattresses that work well for you and some that don’t.
While I can certainly help with “how” to choose … I don’t make specific suggestions or recommendations for either a mattress, manufacturers/retailers, or combinations of materials or components because the first “rule” of mattress shopping is to always remember that you are the only one that can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved that are unique to each person to use a formula or for anyone to be able to predict or make a specific suggestion or recommendation about which mattress or combination of materials and components or which type of mattress would be the best “match” for you in terms of “comfort” or PPP or how a mattress will “feel” to you or compare to another mattress based on specs (either yours or a mattress), sleeping positions, health conditions, or “theory at a distance” that can possibly be more accurate than your own careful testing (hopefully using the testing guidelines in step 4 of the tutorial) or your own personal sleeping experience (see mattress firmness/comfort levels in post #2 here).
When you can’t test a mattress in person then the most reliable source of guidance is always a more detailed conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart and who can help “talk you through” the specifics of their mattresses and the properties and “feel” of the materials they are using (fast or slow response, resilience, firmness etc) and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked or other mattresses you are considering that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs and firmness levels to different body types, sleeping positions, and preferences (or to other mattresses that they are familiar with) than anyone else.
You are certainly looking at some great options and all of them are members here which means that I think highly of all of them and I believe that they all compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency. and there are no lower quality materials or weak links in any of them. Each of them have different options available and some differences in their design and/or the type and blends of latex or the firmness levels they have available as an option and there are also differences in their return/exchange policies as well.
There is also more about the different types and blends of latex in post #6 here and there is more about some of the differences between Dunlop and Talalay in post #7 here but the most reliable way to know which type or blend of latex you tend to prefer will be based on testing a range of mattresses in different firmness levels to see if you can identify any patterns in your experience. In some cases you may find that you don’t have a distinct preference because the mattresses you prefer may depend on other differences in their design more than the type or blend of latex that they use in each layer.
I’m assuming that you’ve read the mattress shopping tutorial but two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort” and PPP that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists based on all the parts of your personal value equation that are most important to you.
Once you have narrowed down your options to a list of finalists that are all choices between “good and good” and none of them have any lower quality materials or “weak links” in their design relative to your weight range (which they don’t) and if there are no clear winners between them (which is usually a good indication that you have done some good research) then you are in the fortunate position that any of them would likely be a suitable choice and post #2 here can help you make a final choice based on your local testing or mattresses you have slept well on, your more detailed conversations about each of them, your confidence about PPP and the suitability of each one, their prices, your preferences for different types of materials and components, the options you have after a purchase to fine tune the mattress or exchange or return the mattress or individual layers and any costs involved, any additional extras that are part of each purchase, and on “informed best judgement” based on all the other objective, subjective, and intangible parts of your personal value equation that are most important to you.
Phoenix