Hi teaelleyou,
You probably already know that I think highly of Dreamfoam in terms of their quality, value, and service and hopefully some of the members here will see your post and respond. In terms of durability, a latex comfort layer is the most durable of all the foam materials and in your weight range especially the Ultimate Dreams would make a very durable choice.
This would be very much of an “apples to oranges” comparison with a latex hybrid mattress. 4 lb memory foam (or even 5 lb memory foam) would also be less durable than the blended Talalay latex in the Ultimate Dreams. Of course the choice of materials is a personal preference and post #2 here has more about memory foam vs latex although your own personal experience is really the best way to know which material you prefer.
There is more about Sleep Science in post #2 here and the posts it links to and more about the Sleep Science 11" Cool Retreat in post #2 here. You’ve probably read this already but in case you haven’t you can also read my thoughts about buying from Costco in post #4 here.
Phoenix