Hi buttercupbelly,
I hae talked with Karl at Sleeponlatex (they are also hahtauctions on ebay) and he is knowledgeable and will provide accurate information about the specifics of his products. I don’t believe they sell mattresses though … only individual layers and components.
There are many different types of latex that use different methods of manufacturing and have different blends of natural and synthetic latex with different costs (which you can read about in post #6 here). Unless two mattresses have the same type and blend of latex and the same design, layer thickness and firmness levels, and the same quilting and cover they aren’t likely to feel or perform in the exact same way in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences). You can read more about matching two mattresses in post #9 here.
Once you have eliminated the worst options and know the specific details of all the layers in each mattress you are considering … you can make more meaningful comparisons between them and make a final choice that is the best match for your specific criteria and risk tolerance.
Phoenix