Hi CLut,
Hopefully you’ve had the chance to read the mattress tutorial which has all the basic information, steps, and guidelines that can help you make the best possible choice … and know how and why to avoid the worst ones.
There are also more guidelines and information in post #3 here and the posts it links to about choosing a mattress if you are in higher weight ranges.
There is more about the most important parts of the value of a mattress purchase in post #13 here but the most important is always how suitable a mattress is for you in terms of PPP and careful testing on a mattress is a much more reliable way to know this than any “theory” about the thickness of a mattress. If the mattress was on a firm foundation then it may have been too firm for you (again you would need to test it to know) but a box spring is an “active” part of a sleeping system so it would have a significant effect on the feel and performance of a mattress. While it’s true that higher body weights will often do better with a thicker mattress … this also depends on the specific design of the mattress and the type of materials that are inside it. There is more about the effect of thickness in post #14 here but what is inside your mattress or all the “active” parts of your sleeping system is more important than thickness alone so the types of overly generalized suggestions that only make thickness suggestions but don’t consider all the other factors that are involved in the design of a mattress that would make it suitable for some people and not others aren’t a reliable way to choose a mattress. The Morgongava uses “mostly natural” continuous pour Dunlop latex made by Mountaintop Foam which is a high quality and durable material that would certainly be durable enough for your weight.
All the “active” components of a mattress will make a difference in how it feels and performs in terms of PPP so if you were to purchase the Morgangava without a box spring and use a firm non flexing foundation underneath it then it would be a different sleeping system than using the combination together. If you test the Morgongava on the floor you will have a much better idea of the difference the box spring makes for you.
The UD Freedom uses synthetic continuous pour Dunlop also made by Mountaintop Foam. While synthetic latex is also a very durable material … it is less “supportive” than their blends which use use a higher percentage of natural latex and most of the configurations of the Freedom would also be softer than the Morgongava as well so I would make sure you have a more detailed conversation with Dreamfoam since they are more familiar with their mattresses than anyone else and would be the best source of guidance about whether the mattress would be a good “match” for you in terms of PPP in one of its firmer configurations. Both the Morgongava and the Freedom can be used on a firm non flexing slatted foundation that has gaps that are less than 3" between the slats.
The tutorial post includes several links to lists of some of the better online options I’m aware of. Posts #3 and #4 here also include links to some of the lower budget latex and latex hybrid mattresses I’m aware of as well. If you let me know your city or zip code I’d also be happy to let you know about any of the better local options or possibilities I’m aware of.
Phoenix