A couple of things that would be interesting to try with this. Artificially increasing the geometry with simple subdivision to give a measure of the impact of

A couple of things that would be interesting to try with this. Artificially increasing the geometry with simple subdivision to give a measure of the impact of geometry on the scene. Do a bloom post-processing filter to give the impression of brighter than maximum. I can see how this might not be considered the point because it's not a ray-tracing solution, but it is a simple screen-space operation that's independent of the technique used to generate the base image. Including such a filter can add a lot of visual appeal, particularly enhancing the lighting benefits of path tracing.