Hi JCapZano,
Thanks for taking the time to share an update … I appreciate it.
I would keep in mind that the perception of firmness/softness is relative and can vary from person to person. For most people the Tuft & Needle would probably feel a little firmer than the medium BME but there are no “standard” definitions or consensus of opinions for firmness ratings and different manufacturers can rate their mattresses very differently than others so a mattress that one manufacturer rates as being a specific firmness could be rated very differently by another manufacturer.
Different people can also have very different perceptions of firmness and softness compared to others as well 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.
Stomach sleepers will tend to do better on “firmer” mattress (not necessarily a “firm” mattress) because the risk of your hips/pelvis sinking down too much and sleeping in a swayback position and putting your spine out of alignment on a softer mattress is higher for stomach sleepers
In very general terms and based on “averages” … side sleepers tend to need a softer mattress because the body has more curves that need to be “filled in” to provide suitable support (such as the waist) and more “pointy parts” (such as the hips and shoulders) that need to sink in more to relieve pressure when you are on your side and generally need thicker and softer upper layers that can contour to the shape of the body more effectively and more deeply. Back sleepers have less curves that need to be filled in (such as the small of the back or lumbar spine) and less “pointy” pressure points and generally do best with a little bit firmer mattress that has either thinner or firmer comfort layers to reduce the risk of their pelvis sinking into the mattress too much which can put the spine out of alignment and cause lower back pain. Stomach sleepers have the flattest and least “curvy” sleeping profile of all and so they tend to need a firmer mattress yet with thinner and/or firmer comfort layers to reduce the risk of their pelvis sinking into the mattress too much and sleeping in a swayback position which can put considerable strain on the lower back and also lead to lower back pain. Stomach sleeping is the “riskiest” sleeping position in terms of back and neck strain (the head is turned sideways which can strain the neck). For combination sleepers the best choice is generally a mattress with comfort layers that are “just enough” in terms of the thickness and softness of the upper layers to relieve pressure points when you sleep on your most pressure prone position (generally the side) but not so soft that the pelvis will sink into the mattress too deeply when you are sleeping on your back or stomach which can put your spine out of alignment.
Having said that … not everyone fits inside the “averages” of other people so your own careful testing or personal sleeping experience and lack of any symptoms or discomfort is the best way to know whether any specific mattress is a good “match” for you in terms of PPP (Posture and alignment, Pressure relief, and your Personal preferences).
There is more about what I call 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 relative to different sleeping positions.
Phoenix