Laser - 5600 most of the time, 8200 sometimes when sniping in Arma 3
1200 dpi Windows
2000 dpi Gaming
300 dpi Sniping
I'm not overly fussed between the two.
However my DPI for pretty much all games is set at 800. Especially in FPS's, the accuracy gained by having to do bigger mouse swipes works nicely for me. Every now and then I will go up to 1600 if I'm having a good day and fancy some extra aiming speed.
Changing dpi messes with my muscle memory.
I stick to one setting.