Hi Cgeorgal,
Yes … if a mattress has different firmness levels on each side and one side is suitable for you in terms of PPP and the other isn’t then in effect you would have a one sided mattress that you could rotate but not flip (unless you added a topper to the firmer side so it was suitable for you). Latex is a very durable material even in a one sided mattress so a two sided version isn’t necessary for durability but even with latex a two sided mattress will last longer than a one sided version of the “same” mattress (see posts #2 and #3 here and the posts it links to for the pros and cons of one vs two sided mattresses).
Mattresses that have two different firmness levels on each side can be useful for those that haven’t tested the mattress or are uncertain which is better for them so they can use their longer term sleeping experience to decide which side is best for them. They can also be useful for those who like to change their sleeping surface from time to time or based on changing preferences or circumstances and would prefer to sometimes sleep on a softer or firmer surface even though it’s not their “usual” preference. They can also be useful as a set of twin XL mattresses to make a king where a couple can have two different firmness options on each side and the two mattresses will have the same height when they are together. Whether this was a positive or negative would depend on each person’s individual preferences and circumstances and on the parts of their personal value equation that were most important to them.
Yes … as far as I know this is unique to them and I don’t know of any other manufacturers that use it. I also don’t know whether their claim that the iodine “aids breathing” based on the slow release of iodine has any validation or evidence when it’s used in a mattress (or if they will provide any evidence to you). It appears to be used in thin layers so it probably won’t affect durability but I have no personal experience or knowledge of it as a mattress material so you would need to rely on your own “best judgement” when it comes to the seaweed.
Phoenix