Hi Pain in Idho,
From a cost of materials standpoint it would certainly be worth it (3" of Talalay latex would cost you more than $238 if you were to buy it separately) but only each person can decide if it’s “worth it” as part of an individual mattress.
Having an extra layer of latex would give you more options for arranging or exchanging the latex layers and would be more durable as well which may be important for higher body weights. It would also be more “adaptive” to different body shapes because latex contours to different shapes more effectively than polyfoam. It would also be closer to the feel and performance of an “all latex” mattress if the top 6" were latex vs only the top 3".
Post #9 here and the posts it links to would also be worth reading and deal with basically the same question. As you can see it would be “worth it” to me if I was making the decision and I could comfortably afford it but my personal value equation may also be very different from someone else so only you can decide whether it’s “worth it” to you.
It may but this would be a secondary issue to me because latex is a very durable material and reversing the layers would also affect the feel and performance of the mattress and once I had found the layering that worked best for me I would keep them in that order. Flipping the individual layers may have a small effect on durability but I would keep them in the order that is best for you.
I also wouldn’t be concerned about the latex shifting (see post #15 here).
Phoenix
PS: I’ve deleted your other post which is a duplicate of this one. I always answer posts in the order of oldest to newest (bottom to top) so adding a second post won’t speed up a reply.