Hi Fish17,
You’re welcome. 
I think you’re getting just a little confused here (which I know can be easy with all of this information), as I specifically quoted information from both Radium and Talalay Global that one considers their blended Talalay more durable and one considered their 100% NR Talalay more durable (It’s in the third paragraph of my reply). Additionally, these differences are so small that I consider all latex (blended or not) to be a high quality choice and don’t make one blanket recommendation of one over another (see the second paragraph of my earlier post). You’ll do well choosing either one.
I think here you’re referring to the difference in compression modulus between the two type of latex. Dunlop does tend to get “firmer faster” than Talalay after the 25% compression mark, so many people consider it to be “firmer” or “more supportive.” Both types of latex offer excellent support, but because of this unique feature in the difference in compression modulus, many people prefer Dunlop in their deeper layers, although I know quite a few who prefer it in their upper layers as well.
All of the layers work together to form an entire system, with the uppermost layers contributing more to overall comfort. There is also more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel” that may be useful as well.
In the system you’re describing the second layer could be called a “transitory layer”, but really the term doesn’t mean anything. As you’re a side sleeper, and if you’re a bit curvier, you may have more of an affinity for Talalay versus Dunlop here. It really is a personal opinion. I would use the expertise of the people at SleepEZ and their experience fitting many clients in similar situations like yours and ask for their opinion.
Talalay is usually referred to by ILD (although a higher ILD will be more dense). It is common for people to use a bit of a higher ILD in their second layer, but not always. Some people prefer a firmer surface comfort, and they go with a bit firmer on top and then a bit softer in the middle. Again, it comes down to personal preference. Dunlop will be denser at a similar ILD to Talalay, so sometimes a manufacturer will recommend Dunlop for a middle layer instead of Talalay, but at the same ILD that the Talalay was going to be, for a bit more “firmness” as things progress down, especially if that person is of a higher BMI. Again, this is where the expertise of a knowledgeable manufacturer comes into play, as they best know what to recommend what tends to have more successful outcomes with their particular componentry.
I want to help you avoid getting too far down into that rabbit hole of specifications. While knowing the specs that can affect the quality and durability of the layers and components in a mattress is always important … unless you have a great deal of knowledge and experience with different types of mattress materials and components and their specs and different layering combinations and mattress designs and how they combine together and can translate them into your own “real life” experience that can be unique to you (which would generally be a very small percentage of people) … I would tend to avoid using complex specifications to try and predict how a mattress will feel or perform for you. When you try and choose a mattress based on complex combinations of specs that you may not fully understand or only based on specs for single layers or components that may not be as relevant or meaningful as you believe it is then the most common outcome is “information overload” and “paralysis by analysis”. Even the best mattress designers in the industry are often surprised at what a mattress they design “should have felt like” based on the specs when they design it and what it “actually feels like” when they test out their new design.
The only way to know whether any specific mattress design or combination of layers and components is a good “match” for you in terms of comfort, firmness, and PPP with any certainty will be based on your own careful testing and/or your own personal experience when you sleep on it. And that’s why I always suggest to use the expertise of some of the more knowledgeable manufacturers here on our web site to assist you in making your best choice. And that is the beauty of having a component system – you have the chance to reconfigure what you have, or order in different layers as time goes on.
Having said that … you can see some general comments about the properties of an “ideal” mattress in post #4 here.
Let me know what you decide to do. I’ll be interested in your final choice.
Phoenix