Hi asjdwf,
These types of choices where you are choosing between “good and good” are really a matter of preference and it would depend on the parts of your “personal value equation” that are part of every mattress purchase (not just the mattress) that are most important to you. Personally, I put a high value on manufacturers that sell mattresses online that have good options after a purchase for either exchanging the mattress or individual layers in case you make a choice that is not as suitable for your needs and preferences as you would have hoped. This would also depend though on your “risk tolerance” and on your confidence in the suitability of your choice. Less options can mean lower prices and for some people price may be more important than any options after a purchase.
The more challenging the circumstances and the more important the most suitable choice may be (and higher weights can be a more challenging variable in a purchase) the more value I would place on these types of options with an online purchase. I would also consider that with higher weights the layers under the top 3" layer will be more important as well (because you will be compressing them more) and it may be worth considering a mattress where the middle transition layer (the materials under the top 3’ latex layer) is a higher quality and more responsive and adaptable material as well.
I would also keep in mind that the exchange policies with the mattresses on their own site that have them are less costly and more liberal than the ones on Amazon that allow exchanges and there are also options there that are not available with their Dreamfoam line on Amazon.
Finally I would make sure that you have talked to them in more detail about all your options because they are more knowledgeable than anyone about which of their mattresses have the best odds of success for different body types and sleeping styles based on the “averages” of their customers that may be similar to you and your own personal testing on local mattresses that have similar materials and designs (if they are available locally) can also be useful in helping you to narrow down your best choices based on your actual experience and testing instead of using “averages” or 'theory".
Phoenix