For games that support raw mouse input, I always disable the WPS field, that's why it's grayed out on some games. When raw mouse input is enabled, the game completely ignores any acceleration and/or point speed settings in Windows.
The reason I disable the WPS field is that mouse sensitivity tend to be very unstable when not using raw mouse input. Meaning moving the mouse X amount of inches gives you a different result every time, instead of a consitent result with raw mouse input on.
You would think having the Windows setting to 1:1 (6/11) and acceleration off is the same as having raw mouse input on, but in a lot of cases it unfortunately is not.