I just have aborted the compile process, after 7 hours at the 2nd bounce of light.
Surprisingly the 28MB lightmaps load for me, but I’m not sure if this will be the case for all other people.
The normal/bump maps look quite dark as well. In some placed the light looks really nice. Like here for example:

On other places the resolution is not the best although I used q3map_lightmapsize 512 512 and q3map_lightmapsamplesize 2. Example:

Here a screenshot showing both at the same time:

In all cases the shader looks quite dark and the normal maps are inconsistent. I really need to think about using this feature.
Maybe I give it a try with q3map_lightmapBrightness 3 or 4.