Hi rdoerner,
Welcome to the site 
I switched your post to a new topic of it’s own so that your questions wouldn’t get mixed in with the other posts in a more general topic.
I’m assuming that you’ve read the mattress shopping tutorial here but 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” and PPP (Posture and alignment, Pressure relief, and Personal preferences) 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).
I would choose the number of layers, thickness, and the firmness levels that both of you would have the best chance of sleeping well on regardless of the thickness of the mattress or the number of layers. There is more about the pros and cons of a thicker mattress in post #14 here and having more layers in post #2 here.
The choice between Dunlop and talalay in any of your layers is also a preference choice more than a “better/worse” choice. There is more about the differences between Dunlop and Talalay in post #7 here but the most reliable way to know which type of latex you tend to prefer will be based on your own local testing.
While your own careful testing or personal experience is the most reliable way to know whether any mattress is a good “match” for you in terms of comfort and PPP, this is only possible ahead of time if you are buying a mattress locally. 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 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.
Both SleepEZ and Foam Sweet Foam are members of this site which means that I think highly of both of them and I believe that they both compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency. You are certainly looking at two great options.
There is more about some of the factors that can affect the price of a mattress relative to different manufacturers or retailers in post #14 here but the biggest factor is generally the type, amount, quality, and cost of the materials and components inside it. Some types of latex are just more costly than others and this (along with the other variables involved in the price) would be reflected in the cost of the mattress. There is more about the different types and blends of latex that can help you make more “apples to apples” comparisons between mattresses in post #6 here.
In your weight ranges you wouldn’t “need” 4 layers of latex although some people may prefer it.
I would focus more on the type and blend of latex that you prefer than on the name of the manufacturer that makes the latex since latex that is the same type and blend that is made by different manufacturers would be closely comparable.
Once you have narrowed down your options to a list of finalists that are all choices between “good and good” and none of them have any lower quality materials or “weak links” in their design relative to your weight range and if there are no clear winners between them (which is usually a good indication that you have done some very good research) then you are in the fortunate position that any of them would likely be a suitable choice and post #2 here can help you make a final choice based on your local testing or mattresses you have slept well on, your more detailed conversations about each of them, your confidence about PPP and the suitability of each one, their prices, your preferences for different types of materials or types and blends of latex, the options you have after a purchase to fine tune the mattress or exchange or return the mattress or individual layers, any additional extras that are part of each purchase, and on “informed best judgement” based on all the other objective, subjective, and intangible parts of your personal value equation that are most important to you.
Phoenix