UMaterialExpressionGIReplace, switches(or used to switch at some point) material networks for lightmass.
Nice! Though, having explict control over surface cache only here would still be beneficial, in my humble opinion.
I do have one question about Lumen. What would be the strategy to make it work in a scene, where most of components make one huge moving object? So far, Lumen’s diffuse system fails to work there at all. Voxel clipmap constantly updates and aliases significantly. Same for irradiance field etc.