I have a 270Hz monitor which I set a custom profile for 250Hz, this is because I wanted to see if on 250Hz the mouse polling rate if I set it to 250 updates would match, but sadly it doesn't.
Still when I use the mouse on normal 1000Hz polling rate and set the display to 250Hz, the movement continuation seems to be most closely aligned. Though it isn't perfect either. I guess because it is a multiple of 250Hz and so the updates match more ideally.

Now a question I have is should we produce 250Hz monitors instead, use higher mouse polling rates (most definitely anyway) or is it even possible to v-sync the polling rate of mice?
With the increase of monitor refresh rate as long as there isnt a perfect phantom array effect yet (so anything below 1000Hz definitely) this appearance would get more and more visible and affect the smoothness of movements. For example if we go for 480Hz instead of 500Hz.