okay. i get it. raytraced direct makes a clean sun shadow in the highrise “windows”. reflections. the skylight was already good but it was noisy. also… in the prior test “renders” i intentionally shot the spotlight into the mirror surface to portrait lumen gi reflecting onto the ground. i reckon in raytraced mode this is too direct (without multiple samples) and will not yield the spread the surface cache has.
and the emissive cubes in my test map look very stable, now. hmmhmm
nice. 
screen percentage is 100% btw. it’s not full blown maps but technically okay in screenspace. and runs cool.