Hi modean,
You are very welcome and thank you for your kind words about TMU. 
I really do believe it is an innocent mistake on sales rep regarding the latex. Denver Mattress has sold many mattresses over the years that used Talalay toppers, these particular ones do not, but they always have new mattresses with new specs, and it is not surprising at all to have some mix-up, especially with your impression he was a stand-up guy.
Not sure why he says that … “there’s no difference in body heat retention between latex and memory foam”. Latex, in general, is the most breathable and the most “temperature neutral” of all the different types of foam materials but of course, the firmness of a mattress and how much you sink into it can also affect sleeping temperature as well. Temperature regulation is a well-covered topic on our Mattress Forum and many people dealing with this issue have given basic experiential accounts of the clear “Heat retention” difference between the two, suggestions and general facts about materials.
Heat retention refers to the amount of heat an object or material can store over time. Sooo…does that mean one would measure the “body (or skin)” retention of heat, or are we measuring the foam materials retention of heat…well you see what I mean. There is more about the many variables that can affect the sleeping temperature of a mattress or sleeping system in post #2 here that can help you choose the types of materials and components that are most likely to keep you in a comfortable temperature range. In very general terms … the materials, layers, and components of a sleeping system that are closer to your skin will have a bigger effect on airflow, moisture transport, and temperature regulation than materials, layers, and components that are further away from your skin and softer mattresses or foam toppers will tend to be more “insulating” and for some people can sleep warmer than firmer versions of the same material.
Let us know how it turns out, great that you are trying it again, hope everything goes smooth and we would love to hear any updates.
Phoenix