Is there any benefit to playing with a super high dpi setting and extremely low in-game settings versus medium dpi settings and medium-low in-game settings? For example: 5700 dpi and 0.7 sensitivity in-game versus 1800dpi and 2.0 sensitivity in-game?
Yeah but there are diminishing returns to how it actually feels. Depends on your resolution and some other factors. You can test it by lowering your DPI to like 800dpi then raise your game sens to compensate, and feel the result. Then switch it around. Raise DPI to max and lower sens and see the difference. Or any DPI in between. Its the sort of thing you have to try for yourself.
To figure out which game sensitivity to use:
(current dpi * current in-game sensitivity) / new dpi = new sens
example with 5700dpi with 1 sensitivity, going to 800 dpi you set it to 7.125:
(5700 * 1) / 800 = 7.125
This is assuming you already have it set to 1:1 pixel (no acceleration) in windows and/or your mouse driver.