Hi cjt,
There are many different cooling technologies that are used in mattresses (memory foam and otherwise) and outlast is just one of them. All of them “work” in combination with other factors to a “degree” but how cool a mattress sleeps in real life is a combination of many factors … some of which have little to do with the mattress and more to do with the person or the bedding that is used on the mattress.
There is a discussion at the end of post #4 here on the three main cooling methods used in mattresses. There is also a more detailed discussion on the many factors in a memory foam mattress that can affect sleeping temperature in post #6 here.
Like all major brand mattresses though … I would also question the value of the Optimum (you can see more about this in post #48 of this topic) and before I considered any major brand I would read this article which may help eliminate most of the lower value choices when you are mattress shopping and help you focus on mattresses (including those with effective cooling technologies) and manufacturers or retail outlets that have better value.
Phoenix