Hi Brototype,
The Denver Mattress iChoice uses a “base mattress” that is mostly latex but it has two different options that you can choose for a topper. One is a latex topper and the other is a memory foam topper. If you tested the memory foam topper then it will be completely different from a mattress that has a latex comfort layer and wouldn’t be a useful reference point for choosing a latex mattress so I would make sure you test the latex topper to confirm that you like the “feel” of sleeping on latex. There is more about the differences between latex and memory foam in post #2 here.
If you slept on the latex topper then you can use the information here as a reference point when you talk with Dreamfoam to decide on your firmness choice.
It may also be worthwhile testing other latex or latex hybrid mattresses that may be available in your area if they are willing or able to provide you with the information you would need to use them as a reference point as well but when you can’t test a specific mattress in person then the most effective approach to choosing the firmness level that is most likely to be suitable for you would be a more detailed conversation with Dreamfoam who can use the information you provide them to help “talk you through” your choices and who will know more about the different options they have and helping their customers match them with different body types, sleeping positions, and preferences “on average” than anyone else (see mattress firmness/comfort levels in post #2 here).
Phoenix