Hi JustMaine,
Yes … Mountaintop makes a range of continuous pour Dunlop latex that use different blends of latex ranging from 100% synthetic to 100% natural rubber and all of them are high quality and durable materials. You can see a video about how they are made here. All of them are also Oeko-Tex certified for harmful substances and VOC’s. There is more about the different types and blends of latex in post #6 here and a forum search on Mountaintop (you can just click the link) will also bring up many more comments and feedback about them as well.
Both of the mattresses you are considering use high quality materials and there are no lower quality materials or weak links in terms of durability in either of them.
If you have confirmed that both of them are a good “match” for you in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) hopefully using the testing guidelines in the mattress shopping tutorial then they would both be well worth considering.
There is also more about the most important parts of the “value” of a mattress purchase in post #13 here that can help you make more meaningful comparisons between mattresses and help you decide which of your “finalists” are the best value choice based on all the criteria that are m0st important to you but I certainly wouldn’t have any durability concerns with either of them.
Phoenix