Hi blackriderx,
You are certainly looking at some high quality options 
The specific difference would depend entirely on how the the 6" + 3" layers compared to the other options you are considering (assuming they are all 100% natural Dunlop) in terms of firmness, layer thickness, the order of the layers, and the type of cover they used. There would be very little difference between two 3" layers and a single 6" layer that used the same type and blend of latex where both of the 3" layers were the same firmness as the single 6" core and had the same materials above and below them and a very similar cover and quilting (see post #2 here) but once you start changing the thickness or firmness of the layers, the mattress cover, or the design of the mattress then there would be a more obvious difference between two different mattresses with different designs or components. The only way to know whether any specific difference would be better or worse for you in terms of PPP would be your own testing or sleeping experience.
You can see some comments about zoned layers in this article and in post #11 here and post #2 here. If the zoning is a good match for you then it can certainly make “some” difference in terms of PPP depending on the specifics of the zoning.
When you are down to finalists that are all choices between “good and good” and there are no weak links in any of them (which there aren’t) and no clear winners between them … then post #2 here may be helpful when it comes time to make your final choice based on all the objective, subjective, and intangible parts of your personal value equation that are most important to you.
Phoenix