Hi meyerba,
Every layer and component of a mattress will have some effect on every other layer and component and on the mattress as a whole so for a mattress to feel the same as another one it would need to have identical layers and components (type and blend of latex, thickness and firmness of each layer, and the same type of cover and quilting material). There is more about the different ways that one mattress can “match” another one in post #9 here but I would be aware that as soon as there are differences between two designs that the results in terms of how they compare can sometimes be surprising or unpredictable. While local testing can give you a much better sense of how different types of latex and different firmness levels can feel in general terms … it won’t tell you what a different mattress will feel like so I would use your testing as a generic guideline not as a specific indication of how another mattress will feel.
Your SO is a little over the weight range (low 200’s) where I would tend to lean towards higher density polyfoam in the base layer such as some of the latex/polyfoam hybrid mattresses that are sold by Brooklyn Bedding which is their sister company. Post #16 here and the posts it links to has some comments that compares the Ultimate Dreams Eurotop and the Brooklyn Bedding Bamboo Bliss for example that may be helpful.
Dreamfoam also has their Natural here which uses Dunlop and has a 2 lb polyfoam base layer.
You can see the specs of the PLB mattresses in post #2 here and the Serenity is the same as the Pamper, the Essence is the same as the Nature, the Elegance is the same as the Beautiful, and the Pristine is the same as the World’s Best Bed.
Phoenix