Hi johnep,
Well done with all the trials, and yes Ken from Arizona Premium Mattress (one of our Trusted Members here) is very knowledgeable with a long history of making latex mattresses and fine-tuning them to match customer needs and preferences.
There would be little if any practical difference between two 3" support layers and a single 6" support layer if they were all the same type and blend of latex and the same ILD and were inside a tight fitting cover with 3" inches of latex of the same ILD on top of them. Two 3" layers would respond a little more independently and because the elasticity of the top 3" wouldn’t be connected and “pulling back” on the bottom 3" when it compresses and “in theory” it may act a little bit softer but in practical and real-life terms most people wouldn’t notice any difference in terms of performance or firmness. If a single 6" core with a 3" comfort layer was a good match for you in terms of PPP then there would be little benefit in having multiple 3" layers that were the equivalent ILD. As long as don’t move to something too soft for the bottom 6" you should be ok.
Two-inch layers, in theory, are definitely enough to give proper performance. Different people have different needs and preferences and one is not better than the other as it’s all about which one is the best match for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences).
Regarding other configurations, it would be very tricky for me or anyone else to begin recommending different configurations, it is really about you matching up what is best based on your research, history, and local testing. … any specific tweaking from TMU cannot be a substitute for this … we typically make sure that you are heading in the right direction, offer some guidance, and provide any necessary supportive information but generally the best and most accurate recommendations always come from the retailers/manufacturers themselves as they are much more familiar with their materials and own mattress designs than anyone else (including me) and they can use the information you provide them about your body type and sleeping positions, your preferences, your history on different mattresses, and the results of your local testing to make suggestions based on the “averages” of other customers that may be similar to you.
I think your view of not going with “all organic” is quite common and many people tend to place this criterion lower in their personal value equation. It 's also worth mentioning there is no Talalay latex in the world that has organic certification but that does not make it less desirable, and whether in its natural, the blended or synthetic version is one of the best foams used in mattresses. It’s important to note that blended is not “bad” by any means and is still a “more natural” product than many others. Most of the blended latex products are 30/70 (sales people just like to say its 70/30) but that is simply not the case with the formulas /manufacturers that have been mentioned. There is also more about organic, natural, green, and “safe” materials in post #2 here and the posts it links to because many people that are looking for “organic” materials are often just looking for materials that they can have confidence are “safe”.
Good luck with the fine tunning and I’d be interested to know what your final decision is!
Phoenix