Hi brosen72,
You’re right that the major manufacturers don’t make the same type of mattresses any more both in terms of the quality of the materials they use in their comfort layers and in the fact that they don’t make two sided mattresses any more. There are still many smaller manufacturers around the country though that still make two sided more “basic” mattresses using higher quality materials.
Memory foam tends to sleep warmer than other types of foam but the type of foam in a mattress isn’t the only factor that can affect sleeping temperature and sometimes even changing the type of mattress protector or sheets you use may make “enough” difference in sleeping temperature, especially if the memory foam is one of the faster responding more breathable types such as yours. Post #2 here has more about the many interacting factors that can affect sleeping temperature that may be helpful or give you some ideas about some of the other things that may be possible solutions outside of exchanging your mattress.
Yes … it uses 3" of continuous pour Dunlop latex (they don’t provide the blend) over a polyfoam support core. The latex would be a durable material and would sleep cooler than memory foam and this could be a reasonable choice for someone in more “average” weight ranges but I would be a little cautious if you are in a higher weight range because I believe the base layer is 1.5 lb polyfoam and if you are heavier weight range that will compress the base layer more then this could become a factor in its durability.
Their latex mattresses use Talalay latex (top to bottom) which is a more “bouncy” or “springy” version of latex than Dunlop (post #7 here has more about the general differences between Talalay and Dunlop). Their support core is also Talalay latex which is also more resilient and “bouncy” than the polyfoam support core in the Optimum you tried. There are many versions of latex and many different designs of latex and latex hybrid mattresses and the amount of “bounce” you feel would vary widely between them but overall both Dunlop latex and polyfoam would be less “bouncy” than Talalay.
These are fairly open ended and very broad questions (much like asking “what should I eat” when there are hundreds or even thousands of choices available) but if you are looking at latex then it may be worth considering Dunlop vs Talalay in either an all latex or latex hybrid mattress and it may also be worth considering a more basic innerspring/polyfoam mattress that is similar to the one you slept on for many years.
There are several options available in the area where you could test both to see how they compare for you. Both Dunlop and Talalay are good quality materials but the choice between them would be a personal preference.
Phoenix