Hi LAH7,
You can read a little more bout the PLB hybrid support core in post #6 here. It’s a very durable material but I’m not so sure it would be more durable than latex in the equivalent firmness. The base layer wouldn’t be the weak link of a mattress anyway so it’s probably a moot point.
Outside of quality control issues at the time of manufacturing … latex is the most durable of all the foam materials. All foam will lose some of its softness and height to some degree over time but latex will do so less than any other foam material regardless of which manufacturer uses it in their mattress. There are other factors involved in durability and longevity though that you can read about in post #4 here.
None that I’ve seen and the base of a mattress is rarely the weak link of a mattress regardless of whether it is polyfoam, an innerspring, latex or any other material that is suitable for use in the base layer of a mattress. The weak link of a mattress is almost always in the comfort layers.
Phoenix