HI matresslessinseattle,
Welcome to the Mattress Forum! 
You’re considering products that all use higher quality and durable materials. The Dreamfoam Ultimate Dreams All Latex and the Luma are more similar in construction to each other (all latex) than the Brooklyn Bedding Best Mattress Ever (polyfoam core with latex on top). As you may be aware, both Brooklyn Bedding and their sister company Dreamfoam Bedding are both members of this site, which means that I think highly of them.
EDIT: Luma is now a member of this site, which means that they are endorsed by TMU as well.
The Dreamfoam Ultimate Dreams Total Latex mattress uses a 6" core of Dunlop or Talalay, with 3" of Talalay latex on top of that, for a total of 9" of latex, at $1799.00. The Luma mattress uses a 6" Dunlop core with two 2" layers of Talalay on top of that (new version just introduced) and then the topper is 3" of Talalay, for a total of 13" of latex, and the new price will be $2795.00. I can’t speak to the reasoning behind any company’s pricing policies, but the additional latex in the Luma would be primarily responsible for the price difference. And yes, most people would say that they feel a difference between 9" and 13" of latex, regardless of configurations.
While I can certainly help with “how” to choose … It’s not possible to make specific suggestions or recommendations for either a mattress, manufacturers/retailers, or combinations of materials or components because the first “rule” of mattress shopping is to always remember that you are the only one that can feel what you feel on a mattress and there are too many unknowns, variables, and personal preferences involved that are unique to each person to use a formula or for anyone to be able to predict or make a specific suggestion or recommendation about which mattress or combination of materials and components or which type of mattress would be the best “match” for you in terms of “comfort”, firmness, or PPP or how a mattress will “feel” to you or compare to another mattress based on specs (either yours or a mattress), sleeping positions, health conditions, or “theory at a distance” that can possibly be more reliable than your own careful testing (hopefully using the testing guidelines in step 4 of the tutorial) or your own personal sleeping experience (see mattress firmness/comfort levels in post #2 here).
While using a polyfoam core on the BME certainly will offer a different overall feel (all layers of a mattress work together to provide comfort), it also is a manner to keep costs more affordable.
I’m not sure what you’ve read since you found the site but just in case you haven’t read it yet … the first place to start your research is the mattress shopping tutorial here which includes all the basic information, steps, and guidelines that can help you make the best possible choice … and perhaps more importantly know how and why to avoid the worst ones.
Two of the most important links in the tutorial that I would especially make sure you’ve read are post #2 here which has more about the different ways to choose a suitable mattress (either locally or online) that is the best “match” for you in terms of “comfort”, firmness, and PPP that can help you assess and minimize the risks of making a choice that doesn’t turn out as well as you hoped for and post #13 here which has more about the most important parts of the “value” of a mattress purchase which can help you make more meaningful quality/value comparisons between mattresses in terms of suitability (how well you will sleep), durability (how long you will sleep well), and the overall value of a mattress compared to your other finalists based on all the parts of your personal value equation that are most important to you (including the price of course and the options you have available after a purchase if your choice doesn’t turn out as well as you hoped for).
While again nobody can speak to how any specific mattress will “feel” for someone else or whether it will be a good “match” in terms of comfort, firmness, and PPP because this is too subjective and relative to different body types, sleeping positions, and individual preferences, sensitivities, and circumstances and you are the only one that can feel what you feel on a mattress … outside of PPP (which is the most important part of “value”), the next most important part of the value of a mattress purchase is durability which is all about how long you will sleep well on a mattress. This is the part of your research that you can’t see or “feel” and assessing the durability and useful life of a mattress depends on knowing the specifics of its construction and the type and quality of the materials inside it regardless of the name of the manufacturer on the label or how a mattress feels in a showroom or when it is relatively new so I would always make sure that you find out information listed here so you can compare the quality of the materials and components to the durability guidelines here to make sure there are no lower quality materials or weak links in a mattress that would be a cause for concern relative to the durability and useful life of a mattress before making any purchase.
I hope that information is helpful to you. Let me know if you have any questions once you read through the material I provided. You’re certainly considering some better quality products.
Phoenix