Hi drewa405,
The previous version of the Tuft & Needle used foam that was in “about” a 2 lb density range (density is normally expressed as a range and isn’t exact) and the nominal density values of the three were about 1.8 and 1.9 lb density. The weakest link of a mattress is the upper layers which are most subject to the stresses of the compression forces that come from sleeping on a mattress and their new design (see posts #2 and #6 here) uses a higher quality/density material in the top 3" of the mattress so if anything it would be very likely to be more durable than their previous version (which would also be a big part of the reason why they increased the warranty from 7 to 10 years).
It would certainly be a suitable choice in its budget range even for those that are in higher than average weight ranges.
Phoenix