Left 4 Dead 2 WPS

I have a question concerning the L4D2 sensitivity calculation as the calculator assumes ingame sensitivity will always be influenced by the Windows multiplier. Now I discovered a rawinput option in the menu, which togles "m_rawinput" plus theres a command called "m_mousespeed" which has the ingame description to enable the use of a Windows multipier, so there are somehow 2 Options that very strangely should do exactly the same thing. Now which is also strange is that most guides i found recommend to disable rawinput but without any further explanation and then the description in the L4D2 calculations says that its actually always influenced by WPS. So im asking how it comes that the calculator says it will be affected and if I might have misunderstood the actual purpose of any of the options since this seems a Little odd.

Thanks