I think the following would solve this (and many more sensitivity problems):
An option to set your cm/360° ratio in the xim config, that way you could have the same sensitivity across all games (unless turnspeed cap prevents this) plus sensitivity changes like sync, polling rate or dpi can easily be corrected as well. Its also much easier to grasp for the user when looking up the configs or sensitivities of other players. I mean most users dont know if a sensitivity of 10 with 16000 dpi refers to a slow, mid or fast sensitivity and how they translate that to their dpi settings.