Ok , so i think i found something.
I activated "Lift Gamma Gain" option and adjusted only the shadows "Rgb Lift" from 1.000 (neutral) to 1.028.
Here are some prints.In game u will see a better difference.
No sweetfx
http://imgur.com/PzM7vD5
Sweetfx with Lift Gamma Gain - look at the clouds
http://imgur.com/tKxdUTc
Normal sweetfx - no clouds , only darkness
http://imgur.com/7C0y5fp
No sweetfx
http://imgur.com/WVl95Au
Sweetfx with Lift Gamma Gain
http://imgur.com/823Pyqu
Normal sweetfx
http://imgur.com/fwiPPm3
Tested also in day time , no washed colors.
Im using Brighter nights from
Dynamic Environment and also i slightly adjusted the game brightness.
Hope its helps.