Hi Ariella,
Thanks for providing your experience/details with your previous mattress. We at Dormio are latex mattress exerts so we can definitely provide you with some answers and hopefully some help in finding a new mattress.
As you have experienced with your current mattress, latex foam is outlasting any other type of material being used in mattresses today. The natural cracking/crumbing that happens to latex over long periods of time is due to the fact that latex is 100% plant derived making it biodegradable! Although a latex mattress should last 20-30 years that does not necessarily mean that the mattress will be suitable throughout that time. Many of us will change over this time period, whether that's weight, fitness, stress, health, our bodies are evolving as we age. Our industry has identified this problem which is part of the reason why latex mattresses are much more complex now than they were 25 years ago.
Once of the biggest questions is
what is the difference between Dunlop & Talalay Latex. The main difference of the 2 is the process in which milky sap from the rubber tree is turned into latex foam. Most Talalay latex on the market is blended or synthetic compared to Dunlop which is always pure. Dunlop latex is heavier and more dense compared to Talalay which is softer and bouncier making it less durable then Dunlop. In terms of over all feel, both processes will be healthier then spring or memory foam. As a dancer, it will be important to have Soft layers closest to the body so that there is no disruption to your muscles/nerves through the night. This can be achieved in both types of mattresses, again I think the main difference will be durability and price points.
Removable covers are commonly used on most latex mattresses and have a zippered design. This allows the sleepers to get into the mattress for flipping or rearranging of latex layers. These covers are usually designed to tightly hold all the internal layers so that nothing shifts while being used. These covers are a very important equation and are usually not wash friendly as it would risk that integrity of the mattress should something go wrong in the wash. What we usually recommend is treating your latex mattress as you would a traditional mattress by using a mattress protector on top of the zippered cover. This will ensure that your investment is protected at all times. There are many options on the market that have washable wool instead of a plastic protection layer, this is definitely a better option to promote over all breathability on your new latex mattress.
Latex, especially Dunlop, is considered to be two-sided. This is done during the baking process. Settlement that falls to the bottom of the tray will contribute to a slighter denser feel, therefore one side may be about 10% firmer then the other side. Many retailers will recommend flipping the layers every year so that the entire layer is utilized where as other retailed will promote flipping for a slight change in firmness. Either way, this is great for longevity because it provides the customer with flexibility over the life span of the mattress.
Many latex mattresses today are made with a balance of Firm and Soft layers, which is very important to ensure a supportive yet comfortable sleep. There are some latex mattresses made with all different levels of density in one mattress cover, which is very beneficial for someone who is either not sure what they might need or for someone who puts high importance on flexibility. Based on your size and weight, I would recommend minimum 10" thick with at least 4" of Soft comfort on top. In terms of support, Medium latex will hold body weights up to 200 lbs therefore you would not necessarily need Firm latex. There is one mattress that comes to mind which I think would be a great fit for your Scoliosis. You would be able to customize the Softness at the Head and Hip and separate entities'. If you'd like some more information on this please reach us directly.
Warranty, trial periods and delivery will vary from retailer to retailer. Each retailer will have different rules in how they go about this, especially if you are not local. Many latex mattresses have the same 20 year limited warranty, but this will also depend on the companies Terms and Conditions. Latex mattresses being organic are in most cases not returnable. Many companies will do an internal layer exchange within a certain period of time, but also will vary depending on the retailer. The shipping cost of a latex mattress will also vary, many retailers will build in the cost of shipping into the price of their mattresses where as other retailers will have a flat rate fee. Both options will likely get the merchandise to your door but will still require set-up/assembly. Due to the nature of the product, shipping individual layers is more manageable and allot easier to handle.
I hope I was able to answer your questions and wish you luck in your research for a new latex mattress! Please let me know if there is anything else you had questions about.
Thanks

Laura