Hi TeamHaydre,
I would keep in mind that the thickness of a comfort layer or of a support layer by itself is only one of many factors that can affect whether a mattress is a good match for you in terms of PPP because every layer of a mattress will have some effect on the feel and performance of every other layer and on the mattress as a whole. With some designs you may do best with a 3" comfort layer while with other designs you may do better with a 2" comfort layer.
Whether an inch in a support layer will make a difference or not will depend on how sensitive you are and where you fall in the range between “I can sleep on anything” and “princess and the pea” and on the type, thickness, and firmness of the other layers as well. If they are an identical type of material and firmness level and if they both have exactly the same comfort layer on top of them and the same type of cover then an inch difference in thickness between deeper support layers will usually make much less of a difference than an inch difference in comfort layers that are closer to the top of the mattress.
There is also more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel”.
Unless you have a great deal of knowledge and experience with different types of mattress materials and specs and different layering combinations and how they combine together and can translate them into your own “real life” experience that can be unique to you … I would tend to avoid using individual specs such as layer thicknesses or ILD numbers or other complex specs to try and predict how a mattress will feel or perform for you and focus more on your own actual testing and/or personal experience. When you try and choose a mattress based on complex combinations of specs that you may not fully understand then the most common outcome is information overload and “paralysis by analysis”.
I would always keep in mind that the only way to know whether a mattress “as a whole” will be a good “match” for you in terms of PPP with any certainty will be based on your own careful testing or personal experience.
There are many manufacturers that do this and many that don’t so it’s not “standard” either way. There is more information about the pros and cons of wrapping individual layers with a thin fabric in post #2 here.
Yiou are certainly dealing with one of the better options in your area (see post #2 here)
Phoenix