I'm the inventor of this product, so I thought I give you some comments on chassis stress. Any laptop stand that creates an airspace underneath the keyboard will generate some stress in the area's that are not supported. From a stress standpoint, supporting the entire keyboard is best. However, from a cooling standpoint, having minimal contact underneath the keyboard will allow for better airflow and thus better cooling. Any place that the keyboard touches is a place that the heat transfers into the support surface, which is then held there, and heat can built up. This stand has a minimal surface area in contact with the underside of the keyboard for maximum passive cooling.

Tony is right that there is some additional stress created by the section that rests on top of the keyboard. However, laptops are not heavy enough for this small amount of additional stress to create a problem in normal use. The stand is super strong, and no doubt stronger than the laptop though, so sitting on your laptop could be a problem and is not recommended ;-)