Hi celestial,
Almost all of the Dunlop latex you encounter will be imported and some of the Talalay latex will be as well (Radium is in Holland and is the other Talalay latex manufacturer you will come across besides Latex International).
As long as it has a recognized certification (typically OekoTex but there are also others such as LGA, Eco Institut, and Eurolatex as well) and you know the type and blend of the latex then I would have no issues of any kind with imported latex.
In terms of durability … latex is among the most durable mattress materials and is the most durable of the foam types (see post #4 here).
Comfort is a subjective term and each person has their own definition but in terms of what I call PPP (Posture and alignment, Pressure relief, and Personal preferences) it would depend on the design of the latex mattress and whether it was suitable for your body type and sleeping style … as well as your preferences. Any material in the right combination and design can be both suitable and “comfortable” for some people and not for others.
In terms of sustainability or carbon footprint it would depend on how it was defined and which of the many steps from cradle to grave of a material are taken into account and measured. There are no clear definitions or answers to most questions that are connected to sustainablilty but there is some good information and links in post #2 here that may be helpful.
I think it would be fair to say that in spite of some concerns with issues like biodiversity or the energy and water required to produce it … latex (and especially 100% natural latex) would normally be considered among the most green and sustainable of mattress materials (along with innersprings and natural fibers).
Phoenix