Hi fdb,
Unfortunately … there is no way for me to know what you would consider to be soft or firm unless you have tested a similar mattress where you know the layering and can tell me how it feels for you as a reference point. All I can say is that for most people the layers you are considering would be on the softer end of the scale. There is more about the difference between Dunlop and Talalay in post #7 here.
As you can see in the post I linked previously … there are too many unknowns, variables, and individual preferences involved so I don’t make specific comfort recommendations. The only way to know which combination is best for you in terms of PPP would be based on careful and objective testing on similar mattresses in a showroom so you have a reference point or with a more detailed conversation with an online retailer or manufacturer who can help you choose the option they have available that you believe would be best for you (see mattress firmness/comfort levels in post #2 here once again).
More layers have more possible combinations than less layers to customize or fine tune a mattress both before and after a purchase (see post #2 here) but more layers can also be more complex and confusing if you’re not sure what to change to make the fine tuning adjustments that are most likely to “solve” any symptoms that you experience when you sleep on a mattress.
Phoenix