Hi Marthasyard,
It sounds like you have an 8" bedframe and using a bedframe with a lower height would also lower the height of your sleeping surface. You could also purchase a bunkie board (that are usually about 2" thick) to lower the height of your sleeping system even further if necessary. For example Flobeds has their slat conversion kit here that has a lower profile.
Every layer and component in a mattress (including the cover and quilting) will affect the feel and performance of every other layer and component both above and below it and the mattress “as a whole” so any differences in the design of two mattresses you are comparing such as the type or blend of latex, layer thicknesses, or layer firmnesses will have an effect on how they compare to each other in terms of “comfort”, firmness, and PPP (Posture and alignment, Pressure relief, and your own Personal preferences).
When you can’t test a mattress in person then the most reliable source of guidance is always a more detailed phone conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests at heart and who can help “talk you through” the specifics of their mattresses and the properties and “feel” of the materials they are using (fast or slow response, resilience, firmness, motion transfer etc) and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked or other mattresses you are considering that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs and firmness levels to different body types, sleeping positions, and preferences (or to other mattresses that they are familiar with) than anyone else.
Yes … changing the type or blend of latex will make some difference in how a mattress feels. The choice between Dunlop and Talalay is more of a preference and budget choice than a better/worse choice. There is more about some of the general differences between Dunlop and Talalay in post #7 here but the best way to know which type of latex you tend to prefer will be based on your own careful testing or personal experience. There is also more about the different types and blends of latex in post #6 here.
You are certainly looking at some good quality/value choices
Phoenix