for those of you who have problems with grainy/splotchy lightmaps.
you can workaround this by upping the indirect lighting intensities of your lights from 1 to 3-6. depends on the lighting situation and the light intensity of the light.
if your scene then gets too bright, you can cramp up the eye adaption/exposure min/max brightness settings. to something like 0.4-0.5 also highly depends on your environment and lighting situation. but this way i can also use the GPU baker in critical conditions.
not ideal, since f*cking with the post process settings will also affect your exterior views and quickly you changed the complete nice lighting settings you had…but well it is a workaround