I don't think polling rate would affect mouse when you are using a custom DPI and Sens. I just upped my DPI from 400 to 500 and it made a world of difference, btw
It doesnt affect the mouse, it can affect old cpu's. Not all old cpu's like getting information send to them every 1 ms (aka 1000Hz polling rate) but it shouldnt be a problem with modern equipment.
Polling rate has nothing to do with dpi nor sens, so Im not sure with you meant with what you said. also upping your dpi is the same as upping your ingame sens, its no sorcery