Hi dosun,
Some people are much more sensitive than others to different softness/firmness levels in different layers in a mattress and there are also different types of softness/firmness (see post #15 here) but most people would feel a difference yes. The differences would be more noticeable if you were sleeping on them directly than when they are underneath other layers and in many cases the support layers are more about what you feel in the morning than what you feel when you are going to sleep at night.
This is not unusual and many people that aren’t used to a latex mattress comment on it. Latex is very point elastic (which means that each area of the surface contours and compresses more individually without being affected or “held back” by the material around it) so it’s normal for it to sink in more deeply when your weight is more concentrated by sitting than with a “stiffer” and less contouring material such as the polyfoam that is used in the support core of most memory foam mattresses. Thinner layers of latex will also become firm more quickly than thicker layers as you compress them more deeply (especially with sitting) so they will go from soft to firm in a smaller range than thicker layers and can feel like they are “bottoming out” even though they aren’t at their maximum compression (you can read more about the effect of thickness in post #14 here). As you mentioned there would also be a difference between Dunlop and Talalay because Dunlop gets firmer more quickly with deeper compression and is less “lively” than Talalay.
Latex is the most “lively” and resilient of all the foam materials and memory foam is the least lively and resilient (it absorbs most of the compression forces instead of storing and returning it) and has the “deadest” feel of all the foam materials. Polyfoam would be in the middle. Dunlop would also be less lively or “springy” than Talalay (see post #7 here for more about the difference in “feel” between Dunlop and Talalay).
If you are looking for a less resilient material than Talalay then either Dunlop latex or firmer polyfoam may be worthwhile considering for the support layers.
I would also keep in mind that a mattress that is too firm and doesn’t contour to your body shape and fill in and support the recessed gaps in your sleeping profile can lead to poor alignment just as easily as a mattress that is too soft and because the goal is always good alignment which means that some parts of the body need to be “stopped” from sinking in too much while others need to be “allowed” to sink in more. Good alignment is always the goal and there is more about the relationship between primary and secondary support and pressure relief in post #4 here.
It may take some trial and error to find the layering combination that you do best with when you are building a DIY mattress (see option 3 in post #15 here) and some careful analysis of each combination you try before making changes but I would make small incremental changes so you don’t skip over a combination that works best for you. I would also use your sleeping experience and any actual “symptoms” you have on the mattress as a guideline for the type of changes that you need because they can be a more reliable guideline than what a mattress “feels like” which is much more subjective. There is more about the typical symptoms that you may experience and some of the possible underlying causes for them in post #2 here.
Are you experiencing any symptoms when you sleep on your mattress (such as lower back pain or other pain or discomfort) or is it more a matter that it doesn’t “feel” the way you prefer?
Phoenix