Hi burner,
No … as long as any softer polyfoam in the upper layers of a mattress are no more than “about an inch or so” then it won’t be a durability issue and there are many people that prefer the feel of a little less resilient foam material in the quilting vs sleeping directly on a more highly resilient material like latex. Once there is 2" or more of softer polyfoam in the top layers then if the polyfoam is lower quality/density it could be a “weak link” in the mattress. The quality/durability guidelines I would suggest using are in post #4 here and there is more about the pros and cons of quilted covers vs thinner knit covers that are more stretchy in post #12 here and the posts it links to.
Both of these mattresses would be very durable choices and there are no weak links in either of them but durability aside … any mattress purchase also needs to be a good match for you in terms of comfort and PPP (Posture and alignment, Pressure relief, and Personal preferences) because there is little “value” in purchasing a mattress that you don’t sleep well on no matter how durable it may be.
There is more about the most important parts of the “value” of a mattress purchase in post #13 here.
When you can’t test a mattress in person to make sure that it’s comfortable and suitable for your body type, sleeping positions, and personal preferences then the most reliable source of guidance is always a more detailed conversation with a knowledgeable and experienced retailer or manufacturer that has your best interests in mind who can help “talk you through” the options they have available based on the information you provide them, any local testing you have done, and the “averages” of other customers that are similar to you. They will know more about helping to “match” their specific mattress designs to different body types, sleeping positions, and preferences and which of the firmness and layering options they have available will have the best chance of success than anyone else.
There is also more about the different ways to choose a mattress (either locally or online) that is the most suitable “match” for your specific needs and preferences and how to identify and minimize the risks of making a choice that doesn’t turn out as well as you hoped for that are involved in each of them in post #2 here.
There is more about the different types of foundations or support systems that are suitable for different types of mattresses in the foundation post here but these were built specifically to work well for “all latex” mattresses and they have less than 3" of space between the slats so they would certainly be suitable for any type of foam mattress (polyfoam, memory foam, or latex foam).
Phoenix