Hi Adidas,
Talalay is not as dense as Dunlop in the same firmness level or ILD. You can see a comparison for example of the densities of LI blended Talalay and Latex Green 100% natural Dunlop in post #2 here. In practical terms I would also consider Talalay and 100% natural Dunlop to be close equivalents in terms of overall durability and you may find that because of the many factors that are involved with durability that in one case a Dunlop latex mattress will be more durable and in another case a Talalay latex mattress will be more durable depending on all the variables involved but both are very durable materials. There is more about the many variables that can affect durability and the useful life of a mattress in post #4 here and there is also more about the different types and blends of latex in post #6 here.
Either one can be just as “supportive” as the other one depending on the firmness level and what you mean by “support” although Dunlop has a higher compression modulus which means it gets firmer faster with deeper compression than Talalay. You can see more about how they compare in post #7 here.
I would also be aware that firmness and support are not the same thing because it depends on which part of the body you are talking about and a material that is too firm may provide poor support under the more recessed parts of the body (see post #4 here).
As he also mentioned … there can also be more inconsistency in the firmness of Dunlop layers that are cut from the bottom or top of a 6" core or across the surface than with Talalay (see post #6 here).
Phoenix