Hi SudOvest.
I have deleted your duplicate post as your questions are relevant and added a new dimension to current topic so the “piggybacking” is relevant and quite appropriate
As your daughter is fast approaching the 3 years old mark she’d be more in the medium-firm to medium ranges of comfort suitable for her age. Generally, there is no single firmness level that is always best for all children and different people or different manufacturers can have different definitions of firmness. This said sleep Ergonomic research will recommend for babies and infants a firm to extra firm sleeping surface while toddlers generally need a medium-firm to firm sleeping surface and older generally do best on a medium to medium-firm sleeping surface. There is more complete information on this subject in post #2 here.
These 4 options could still work but it still depends on each child and on your criteria of selection and what is most important to you.
The “reverse layer” arrangements (medium Talalay on top of the soft Talalay, medium Dunlop over soft Talalay, and …also medium Talalay over soft Talalay arrangements) the medium layer on top of a soft layer will reduce how far your daughter sinks through the upper layer to feel the effects of the softer layer below which can work well in certain cases, but I would have some reservations as to the level of support that’s appropriate for your daughter’s development. The advantage of such layer arrangements is that in about 10 years from now when your daughter develops more adult proportions you can simply switch of the layers for a plusher comfort level. Out of the above 3 arrangements, I would favor Dunlop medium on top as Dunlop is considered to be more supportive because it doesn’t compress as deeply with greater weight
The other version you are considering Medium Dunlop over Medium Talalay would conform more with the general recommendations for growing children, Dunlop latex compresses at different rates for different masses (all foams respond to “weight”), and it’ll feel softer initially in the first 25% or so of compression, and then firms up faster (has a higher compression modulus), As your daughter grows, her BMI increases and she’ll compress the top layer past the 25% mark when the Dunlop on top will start feeling firmer at which point you can flip the mattress for a softer feel placing the Talalay layer on top. As opposed to Dunlop when Talalay is compressed past 25% of its thickness will feel softer than its Dunlop counterpart. This option has the advantage of making a more gradual change and more in tune with the general recommendations for growing children.
Children have different proportions than adults have, and also their weight is generally more evenly distributed which means that they won’t have pressure point issues and the “need” for a softer layer to form a cradle and contour around their profile nearly as much as adults would. Children have less mass so “theoretically” everything will tend to feel a bit firmer for them, but again growing children can adapt to almost anything so I personally would lean toward firmer sleeping surfaces for multiple reasons. Infants and children spend more time on a mattress, have a much more flexible spine that is less curvy than an adult, a child needs to be better supported than an adult by the surface layers, and they also need a mattress that allows for free movement (especially for very young children).
As for a comfort recommendation you received, every child is different but, I would give strong consideration to what Henry and Sleep EZ advise, as it does dovetail with generally accepted sleep ergonomic guidelines for a toddler.
Latex is the most durable of all foams and with good protection at your daughters’ weight, it is very likely that it can last for several decades.
Phoenix