Hi ps99115,
Thanks for taking the time to share another update … I appreciate it 
[quote]From my DIY adventure, I have an additional 3 inch xfirm blended talalay topper and a cotton/wool sleep ez 10 queen cover. I’m considering buying 6 more inches of latex to build a new mattress for the guest bedroom and to possibly improve upon our current design if needed. For that I was considering three 2 inch toppers for the top 6 inches in the following firmness;
Soft/med/firm/xfirm (3 inch), top three layers are 2 inch.
Would this be significantly softer than our current bed of med/firm/med (all three inch toppers)? I’m assuming the adjustability would be greater with the 2 inch toppers. Is there any disadvantage to having a 2 inch topper as a transition layer versus a 3 inch topper.[/quote]
Different people can also have very different perceptions of firmness and softness compared to others and a mattress that feels firm for one person can feel like “medium” for someone else or even “soft” for someone else (or vice versa) depending on their body type, sleeping style, physiology, their frame of reference based on what they are used to, and their individual sensitivity and perceptions. There are also different types of firmness and softness that different people may be sensitive to that can affect how they “rate” a mattress as well (see post #15 here) so different people can also have very different opinions on how two mattresses compare in terms of firmness and some people may rate one mattress as being firmer than another and someone else may rate them the other way around. This is all relative and very subjective and is as much an art as a science.
Having said that … I would guess that the layering combination that you are thinking about would feel “noticeably” softer than the combination you are currently sleeping on.
As you mentioned more layers would also give you more options to rearrange layering combinations as well.
All the layers and components of a mattress will compress simultaneously (one doesn’t start compressing when the ones above it are “finished” compressing) but they each compress to a different degree or percentage of their thickness based on their firmness level, thickness, what is above them, and how deep they are inside the mattress. The amount they all compress together will contribute to how much different parts of your body sink in to the mattress and the depth of the pressure relieving cradle which in turn will affect the comfort and pressure relief and the secondary support of the mattress. Softer layers compress more than firmer layers, thicker layers compress more than thinner layers, all layers compress less when there are thicker or firmer layers above them, and upper layers compress more than deeper layers.
Terms such as “comfort layers”, transition layers, and “support layers” are really only generalities and don’t necessarily apply to specific layers or layer thicknesses. For example for some people (depending on body type and sleeping positions) the top 3" of a mattress may provide most of the pressure relief in a mattress even if this doesn’t match the specific thickness of an individual layer. The bottom layer would typically be called a support layer because it will have less of an effect on how the mattress “feels” when you lie on the mattress. The layers (or parts of layers) in between would affect both pressure relief and primary support to different degrees.
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/alignment” and “comfort/pressure relief” and “feel” and how they interact together.
In other words … which layers are comfort layers, transition layers, or support layers is less important than how the mattress “as a whole” meets your specific needs and preferences in terms of PPP.
Phoenix