Hi t-man,
While latex is more durable than other types of foam … with your heavier weight all mattress materials will soften and wear more quickly. In addition to this … you will also likely need a firmer support core than average and I would probably suggest the PLB over the Denver Mattress models because the support core of the PLB is 36 ILD (firmer) while the Aspen is 32 (a little less firm). The greater latex content and thicker mattress will also make the mattress more adaptable to your larger body type.
Both have some fairly soft comfort layers on top (and softer latex will wear faster than firmer with your weight) and I would be very careful to test for good alignment on both of them to make sure you aren’t sinking in too far with your pelvis area which could lead to misalignment (some suggestions for testing alignment are in post #11 here).
It may also be worth considering working with one of the online members of the site listed in post #21 here who can help you choose a mattress which is most suitable for your higher weight. Some of them them also offer a side to side split where each side of the mattress is customized for each person.
If you let me know the city or zip where you live I may also know of some local manufacturers close to you who may be able to customize a mattress for your specific needs.
Phoenix