Hi scg,
You can read some of my thoughts about Diamond Mattress in post #2 here and the posts it links to.
With the Ethos Peace you would need to know the specifics of the other layers in the mattress besides the 2" layer of latex to identify any potential weak links in the mattress or make meaningful comparisons to other mattresses. Hopefully the retailer will be able to call Diamond and find this out for you. If you are able to find out the information and list the layers on the forum (from top to bottom) then I’d be happy to make a few more specific comments about the Peace. Ecoflex is polyfoam that has replaced a small percentage of the petrochemical polyol (one of the two main chemicals used to make polyfoam) with a polyol that is synthesized from a plant oil. there is more about so called “plant based” foam in post #2 here.
Post #2 here has more about the pros and cons of a latex/polyfoam hybrid vs an all latex mattress
This would really depend on the specifics of the mattress (once you’ve been able to find out what is inside it) and how it compared to the other online options you have available and the criteria of your personal value equation that are most important to you along with your comfort level with an online purchase. The first step though would be to find out the thickness and the quality/density of all the polyfoam layers that are inside the Peace so you can make sure it doesn’t have any weak links and so you can make some meaningful comparisons with other mattresses.
Phoenix