Hi Turtlebed,
My comments and reasoning was based on your feedback about each combination and on the lower risk involved with purchasing a mattress that you have confirmed with your own personal testing is a good match for you in terms of PPP vs taking the chance of choosing a mattress that seems to be a less suitable choice and relying on the additional uncertainty and risk of buying a topper where you can’t test the combination in person. Post #13 here has more about the most important parts of the “value” of a mattress purchase and PPP would always be my first priority. Of course you may still be comfortable with a higher risk approach but this is something you would need to decide.
Both of them are good quality choices and have no weak links in the materials which is all I can really speak to. Again … only you can decide which one would be the best match for you in terms of PPP and all the other objective, subjective, and intangible parts of your personal value equation that are most important to you and where in the range of risk you are most comfortable.
Yes it is available.
Arizona Premium may have some 3" organic Dunlop layers (you can call and ask)
Latextoppers carries them
Pure Green Natural Latex Mattress Topper | SleepOnLatex may also carry them (I’m not sure if their Dunlop is organic or 100% natural so you would need to ask)
Organicandmore carries some as well but I believe they only have 2".
Phoenix