Hi roguedog,
Just in case you haven’t read it yet … the tutorial post here is the best place to start and has all the basic information, steps, and guidelines that can help you make the best possible choices. It also includes a link to a list of the members here that sell a wide range of latex mattresses online that have many different features and options.
There are many Dunlop latex manufacturers around the world and most of them make molded Dunlop (Dunlop latex that is poured in a mold). they can be either natural latex or synthetic latex or a mix of both. None of them make their Dunlop cores in the US (they are often made closer to the source of the natural latex itself). There are also two Dunlop latex manufacturers that make Dunlop latex using a continuous pour system (the latex is poured on a belt instead of in a mold). One of these is Latexco and the other is Mountaintop Foam. Latexco makes a blend of synthetic and natural Dunlop and can be poured in layers up to 4" thick and doesn’t use pincores to cure the latex (the layers are thin enough that they don’t need pincores to cure the latex but they can be punched in afterwards). These are usually used as softer comfort layers. Mountaintop has a range of different blends from 100% synthetic to 100% natural and several in between and can be poured in thicknesses up to 7" and uses pincores on the belt to cure the latex. They have a wider firmness range and because they come in a wider range of thicknesses they are more often used as either comfort layers or support layers.
You can read more about the different types and blends of latex in post #6 here. Different types of latex have a different “feel” and performance. As a general rule … natural latex is more elastic and less “stiff” than synthetic latex and Talalay is more “springy” and resilient than Dunlop (see post #7 here).
Cozy Pure uses very high quality 100% natural Dunlop that is made in a mold. you can see some of my thoughts about them in post #11 here. In addition to the 100% natural latex they use very high quality fabrics in all their mattresses.
Nest Bedding uses continuous pour Dunlop made by Mountaintop foam and offers either 100% synthetic or 100% natural. One of the members here Spindle Mattress also uses either synthetic or 100% natural latex made by Mountaintop (Note: Spindle is now only using 100% natural continuous pour Dunlop in their mattresses).
Flobeds uses either blended or 100% natural Talalay latex. They are also a member here and their vZone has a very unique zoning system that can be customized for each person (see post #4 here).
All of these manufacturers use different designs and materials and each have different benefits but they are all high quality options.
All forms of latex are high quality materials and warranties have little to do with the useful life of a mattress (see post #174 here) which has more to do with the materials and design of the mattress. There is more about the factors that can affect durability and the useful life of a mattress and how it is relative to each person (the same mattresses will last longer for some people than others) in post #4 here. The construction of a mattress and the quality and durability of the materials inside it are a much more important and a more reliable indicator of durability than a warranty.
In normal use 100% natural Dunlop is a very durable material that would be equivalent to Talalay in terms of durability (see the video here about a Dunlop latex mattress that was in use for almost 50 years as just one of many similar examples).
Dunlop and Talalay have different cell structures (Talalay has rounder cells with thicker cell walls and more air in the material while Dunlop has a more irregular cell structure and more rubber and less air) so under the specific conditions of continuous compression over a period of years with higher heat and humidity (called heat aging) it would be more susceptible to impressions but this doesn’t reflect real life use. I would have no durability concerns with either material.
You can read more about the pros and cons of one sided vs two sided in post #3 here. if there is a different “feel” on each side of a two sided mattress then it’s more likely that someone would only use the side that is the best match for them and the durability benefits of flipping a two sided mattress would be lost.
A convoluted layer is softer than the same material in the same ILD in a non convoluted layer. It also has a different “feel” than a softer layer because it’s softer when you compress the part that is convoluted and then gets firmer more rapidly as you sink into the solid part of the layer. There is more about convoluted layers in post #2 here.
Hope this helps 
Phoenix