Hi HeatherinMI,
There are no lower quality materials or weak links in the mattress that would compromise the durability or useful life of the mattress for any weight range either with or without the convoluted base foam. The change is relatively minor and for some people (more with heavier weight ranges) may improve edge support.
As you can see in the durability guidelines here … the 2.0 lb polyfoam they use in the base layer is a good quality and durable material that would be suitable for any weight range.
The only reliable way to to assess the “safety” of different materials in more general terms is based on lab tests and the certifications they have for harmful substances and VOCs so that you have some assurance that the VOCs are below the testing limits for the certification (see post #2 here for more information about some of the more reliable “safety” certifications). If the materials in a mattress or the mattress itself has a reliable “safety” certification then for most people they would certainly be “safe enough” … regardless of the type of material or the name of the manufacturer on the label.
The latex in the BME is certified by Oeko-Tex and the polyfoam is certified by CertPUR-US so there would be no reason for concern in terms of harmful VOC’s.
Phoenix