Hi berserkr,
Just in case you haven’t read it yet … the tutorial post here has the basic information, steps, and guidelines that can help you make the best possible choices.
Arizona Premium is one of the members of the site which means I think very highly of their knowledge and experience and they compete well with the best in the industry and have some great value choices available. The tutorial post also includes a link to the other members here who also sell mattresses (including latex) online.
When you can’t test a mattress in person (or a very similar design that you can use as a reference point) then it’s important to make sure you have a more detailed conversation with the retailer or manufacturer about the options they have available that may work best for your body type, sleeping positions, and preferences. They know more about their mattresses than anyone and are in the best position to help you choose the design that has the highest odds of success in terms of PPP based on averages of their customers that are similar to you (see mattress firmness/comfort levels in post #2 here).
Phoenix