Hi firtree,
Yes … if it was me I would replace the top layer.
A 2" topper would reduce the amount you sink in and the amount you were engulfed. Your lighter weight would increase the odds of success with a thinner top topper but it would still depend on your body type and the length of time you spent in each sleeping position.
Yes … this would be important. It would be very rare for someone to have a heat issue with a wool topper on top of latex but as you know every “rule” has its exceptions and for the exceptions the 'rule" means nothing. Hopefully trying to sleep without your comforter can provide insights about whether the heat is being “trapped” in between your bedding and the mattress.
Gel memory foam is an emerging category with many new variants being introduced and there are already many different versions of gel memory foam inside the category each with their own unique characteristics.
Your question is also complex because gel materials regulate temperature in different ways.
There are mainly two types of gel. One of these conducts heat from the body (like putting your hand on a marble countertop) and is “thermal conductive”. It transports heat directly away from the body and releases it into the surrounding atmosphere (as long as it is cooler than the gel) without needing something to “carry” the heat away.
The second is phase change gel (or other phase change materials) which is a little different. It either absorbs heat and becomes more liquid or releases heat and becomes more solid (changes phase with different temperatures). These need to be “encapsulated” with another material so they don’t “leak” when they are semi liquid. These tend to regulate temperature in both directions (cooling or warming depending on circumstances and on whether they are absorbing heat or releasing heat).
The third “cooling” technology is ventilation and moisture wicking which transports humidity and moisture (and the heat it contains) away from the body and either stores it inside a natural fiber (like wool) and away from the body or releases it to the surrounding atmosphere where it is dispersed. The water vapor is what transports the heat away from the body. If the water vapor and moisture is transported and/or stored away from the body then the humidity levels closer to the body are lower and more water vapor can be produced (perspiration) in response to excess heat which keeps the cycle going. Lower humidity levels next to the skin are more cooling than higher humidity levels (just like going outside on a hot humid day feels hotter than going outside on a hot day with the same temperature where the relative humidity is lower).
Lower humidity levels continuously allow more water vapor (and the heat it contains) to disperse into the air or be stored inside natural fibers (which in turn release them into the air more gradually) and away from the body so this type of cooling lasts throughout the night. This is the reason that wool is a great temperature regulator because it traps air which is an insulator when it is too cold but also allows humid air and moisture to be transported away from the body or stores moisture inside the fiber which keeps it away from the skin and keeps the cooling cycle going (which is why it is used in both cold and hot climates).
The first two “gel cooling technologies” are more temporary. In other words they will cool at first for a while until the temperatures equalize and then the foam would once again become an insulator and trap heat. It may provide an extra cooling effect when you are first going to sleep and the foam will feel cooler to the touch but neither of the gel technologies provide as long lasting cooling benefits as moisture wicking, storage, and ventilation. The higher the percentage of gel the more effective and longer lasting the effects of the gel will be.
One of the variables in the different gel materials besides the type of gel is the percentage of gel that the foam contains and this information isn’t disclosed by the foam manufacturing companies so you can’t compare them based on specs. Some types of gel memory foams may contain only 5% to 10% gel which would be a more temporary effect while others may contain 25% - 30% gel which could provide several hours of cooling benefits (again depending on other variables including ambient temperatures and the heat produced by the person sleeping on the mattress). In addition to different gel percentages … some memory foam is also more open celled than others and even with gel memory foams ventilation is an important part of how they work (so the heat can be better dispersed). When the specs of a material aren’t available then you are dependent on the knowledge and experience of a manufacturer or retailer that has your best interests at heart rather than the majority of salespeople in the industry that are only repeating the marketing stories they have been taught to sell a mattress.
Overall though and speaking as a category rather than for specific versions of material in each category (where the technical information isn’t available) … Talalay latex is more breathable than memory foam and less “insulating” so while it may not be as cool when you first go to bed or when you touch it … over the course of the night it will sleep cooler than other types of foam materials including most gel memory foams. Of course this is just a general comparison between the two materials because the overall sleeping temperature of a mattress also depends on the other layers and materials that are in the upper layers including the foam, or natural fibers in the comfort layers, the quilting in the mattress, the type of mattress cover material, the type of mattress protector used, any toppers used, the sheets, and the bedding which all have a combined effect on sleeping temperature and the ability to either store or disperse moisture and heat. There is more about all the variables that can affect sleeping temperature in post #2 here.
Phoenix