Hi kimbeck,
Post #2 here has more information about the different factors that combine together in a sleeping system that will affect temperature regulation. While Talalay is generally the most breathable type of latex … the type of foam in a mattress is only one of the variables that combined together can affect sleeping temperature.
Latex is certainly a more “on the mattress” material than other types of foam (particularly memory foam). Firmer layers will be more “on the mattress” than softer layers but they will also be less pressure relieving.
I would keep in mind that there are no specific definitions for what a “medium firm” actually is and the firmness ratings from different manufacturers may be different from each other. Different people can also have a very different experience on the same mattress depending on body type, sleeping position, and individual perception so a mattress that feels “medium firm” for one person may feel “soft” for someone else and “firm” for someone else. It can also depend on the type of firmness/softness that different people may be sensitive to (see post #15 here). Your own testing or experience based on your personal assessment of “medium firm” is the only reliable way to assess how a mattress feels for you.
I’ve been looking for a local store that would carry a mattress made with Talalay to try it out – do you have any suggestions for stores (chains or locally owned in western PA) that’d carry something similar?
If you are in the Pittsburgh area then the better options or possibilities I’m aware of are listed in post #2 here.
A mattress pad can be a good idea if you want to change the feel or performance of your mattress (add some softness) but isn’t as good an idea if your mattress is already a good match for you in terms of PPP and you don’t want to change how it feels. There is more about the different types of mattress pads in post #10 here but if you are looking for a thinner mattress protector that will have the least possible effect on the feel of your mattress then post #89 here has more information about the pros and cons of the different types of mattress protectors. Wool is a very good temperature regulator.
Mattress encasements and toppers are both different from mattress pads and mattress protectors. A topper would be even thicker than a mattress pad and would have an even bigger effect on how the mattress feels. There is more about dust mites and allergies in post #2 here and there is more about mattress encasements in post #2 here. If temperature is a primary concern to you and you want to change how your mattress feels as little as possible I would tend to use a mattress encasement that protects from dust mites made from natural fibers that didn’t have a semi breathable membrane and then add a more breathable mattress protector (such as a wool/cotton protector like the St Dormier) over it that can be easily removed and cleaned to keep our sleeping surface clean and hygienic so you don’t have to remove the encasement.
This appears to be one of the “thin membrane” type of encasements that would be less breathable than the ones that don’t have a semi breathable membrane and it also appears to be padded with lyocell and polyester fibers which may have more of an effect on your mattress than a mattress protector that isn’t padded (although I’m not familiar with it personally). Polyester also tends to sleep warmer than natural fibers although in this case it appears to be a blend.
Phoenix