Currently, I find myself using maps that are a mix of indoor and outdoor locations.. such as infiltrating a building from the outside. In these cases, the Global Illumination setting does not work that well. Global Illumination works for maps that are either indoor-only or outdoor only, as the lighting these will be uniform (so Global Illumination is On or Off). Mixed maps, however, would be best suited to having Global Illumination apply only to part of the map. Being able to designate on the Dynamic Lighting layer regions that are "excluded" from the Global Illumination I think fits the model.