Hi looking4d,
The Eco series are made by Anatomic Global which is owned by FXI which is a US based foam pourer that is CertiPur certified. I have often had difficulty finding out accurate specs for the Anatomic Global mattresses and in some cases they seem to round up the foam densities to the nearest higher round number but I believe that the memory foam layers are mostly in the 3.5 - 4 lb range or the 4.5 - 5 lb range (depending on which layers). I believe their polyfoam transition layers are in the 1.5 lb range. I don’t know the density of their base layers. I would make sure you can confirm all these numbers with the retailer you are buying from or the manufacturer (see this article).
Memory foam is too soft to be used as a support layer in a mattress so you will only find it in the comfort or transition layers and there will always be some type of firmer support layer or component (polyfoam, latex foam, or an innerspring) under the memory foam for support.
There are also 3 types of foam which are polyfoam, memory foam, and latex foam and all of them are equally “foam” (meaning a material with air bubbles inside it) so it really depends on which specific type of foam mattress you are considering. Which type of mattress you tend to prefer and the mix of different materials and components would be a personal preference (not a better/worse choice). There is more about the most important parts of the “value” of a mattress purchase in post #13 here but as long as any mattress you choose is a good match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences), uses good quality and durable materials (regardless of the type of materials), and compares well to other mattresses you are considering based on the parts of your personal value equation that are most important to you … then it can make a good choice.
I would always make sure that you know the specifics of all the materials in any mattress you are considering to make sure that any foam layers are a suitable density/quality and that there are no weak links in the mattress. I would also be cautious about Lucid and I would read post #6 here and post #2 here along with this topic and the posts they link to before considering them. A forum search on Lucid (you can just click the link) will also bring up more information about them as well.
I don’t have a list of mattresses sorted by materials and I would also keep in mind that there are hundreds of latex and memory foam combinations that would be very different from each other depending on the type, firmness, thickness, and order of the foam layers but off the top of my head My Luxury Mattress and Christeli and Casper and Sleep Science all have a latex/memory foam hybrid of one type or another that use different types and combinations of latex and memory foam. You could also replace one of the latex layers in the Aloe Alexis here with memory foam as well so you would have a combination of both materials. Another option would be to use a latex topper on top of a memory foam mattress or a memory foam topper on top of a latex or latex hybrid mattress and you would also have a memory foam/latex “hybrid” sleeping system as well.
This would depend on what you mean by equivalent. There is more about the many different ways that one mattress can “match” another one in post #9 here but if you are looking for equivalent quality/durability then a mattress that used the same type and quality of foam layers would be equivalent in terms of durability even though it may feel and perform very differently.
If you are looking for a mattress that is “equivalent” in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) and how it “feels” then the only reliable ways to find a mattress that was a “close approximation” would be to find a manufacturer who makes a mattress that was specifically designed to be equivalent to the Eco 2 and specifies this in their online description (which isn’t likely because the Eco 2 isn’t popular enough for a manufacturer to use it as a reference point in their design), talk to an online retailer or manufacturer that is very familiar with the Eco 2 and has specifically compared it to the mattresses they sell, or test both mattresses in person in a side by side comparison so you can “feel” how close they are in person.
I would also be aware that these types of comparisons can be very subjective and can vary depending on each person’s body type and sleeping positions so two mattresses that feel similar to one person may feel different to another.
Phoenix