Hi rudy1337.
Welcome to our Mattress Forum! 
and thank you for your appreciation.
I moved your post to a different thread which discusses some of the products you are considering.
With the classical “him” and “her” different preferences and combination sleeping a side-by-side split seems to be a win-win for both.
[quote] Our thoughts is going with a 4-layer, it will give us the maximum options for customizing.
When comparing the SleepEZ and the Flexus, is the second layer being a Talalay worth the price differential of $350?[/quote]
As for “worth”, while price is certainly important of course … the “value” of a particular purchase is what is most important and price is just one of many factors that can affect the “value” of a mattress purchase. There isn’t a “formula” that can be used to assess or “calculate” the value of a mattress because there are so many different variables and criteria involved that can affect the price of a mattress that can each be more or less important to some people and not to others who may have completely different criteria or definitions of “value” and only you can decide this based on your personal value equation and all parts that are most important to you (including the price of course, adjustability, and the options you have available after a purchase if your choice doesn’t turn out as well as you hoped for).
Talalay in the same ILD as Dunlop will be less dense (will weigh less than Dunlop per cubic foot of material) because it has more air in it. (Talalay vs Dunlop would be like angel food cake vs pound cake) Although they both have the same general properties they will feel slightly different, with Talalay being considered springier and with a softer overall feel than Dunlop in the same ILD… Some people like the feel of it some don’t and you have to test it and assess if this important to you. Talalay is also more expensive to produce with the natural version being more extensive than the Synthetic alternative called Styrene Butadiene Rubber (SBR) or Blended. The natural version is more difficult and lengthy to obtain and work with. Keep in mind that the Top layer is where you would notice most of the differences between the two.
For Talalay … the higher ILD’s use proportionally more latex (are denser) so the cell walls are thicker and more elastic. This in combination with the fact that higher ILD’s are usually used in the core of a mattress where there is less mechanical stress on the material means that it is probably a tossup and because of its better performance I would say the NR has better overall properties than a blend in higher ILD’s but of course also more expensive and the practical differences between them may not justify the increased cost.
Talalay is also more open-celled than Dunlop and would be more breathable and has a more consistent, even, and stronger cell structure because even though there is less latex overall … the cell walls or “struts” are thicker and more consistent. For a more in-depth look there is an interesting post by FloBeds one of our Expert Members which points to some of the “differences” between the Talalay and Dunlop, and you may wish to peruse to see if this would justify the price differential according to your personal value equation.
You can also read more about the differences between Talalay and Dunlop in Post #7 here
As you probably are already aware, both SleepEZ and Flexus Comfort are our Trusted Members here which means that I think very highly of them and that I believe that they compete well with the best in the industry in terms of their quality, value, service, knowledge, and transparency. They are extremely knowledgeable about latex and different configurations, and I would advise you to have a detailed phone conversation with either of these companies before making a purchase in order to confirm your choice of comfort layers.
I’d be interested to learn of your eventual decision
Good luck!
Phoenix