Hi cviz,
The first place I would start is post #1 here which has the basic information, steps and guidelines you will need to make the best possible choices. It will also help you avoid the worst choices including the major brands which you are considering.
With your higher weight it will be important to make sure that any mattress you are considering uses the highest possible quality materials … especially in the comfort layers … because lower density materials won’t last under the stress of your weight no matter how they may feel in a showroom. Unfortunately the specs you listed don’t include the quality of the materials … only the type.
I would also be very careful to make sure you test every mattress carefully for PPP (Posture and alignment, Pressure relief, and Personal preferences) and not just for “comfort” because all of these mattresses are very soft and could be 'risky" for you … especially in terms of alignment.
Yes … latex and memory foam are very different (see post #2 here) and it would be fair to say they have more differences than similarities. It would be well worth testing a latex mattress locally if there are any available.
Generally the best odds of success are to work with smaller independent manufacturers that either sell factory direct or through better sleep shops. They tend to have much more knowledge and experience in helping their customers make suitable choices and are usually more focused more on educating their customers than “selling” them whatever they can convince them to buy. If there are none of these available locally then it may also be worth considering an online purchase rather than purchasing a mattress that is not the quality or value that you need.
If you let me know your city or zip I’d be happy to let you know of any of the better options I’m aware of in your area.
Phoenix