The MM has high DPI tracking (I guess like a gaming mouse) unless like yours, theres a problem with it. I also have a Logitech wired mouse I keep connected as a backup. If the tracking is set to use the MM with it's high DPI then the Logitech with its relatively low DPI is like pushing through mud. Conversely if I set an acceptable tracking speed for the Logitech the MM becomes totally uncontrollable with an enormously high tracking speed.
So all I can say is if you MM has a problem, and it is under warrantee, I see no reason to get apple to exchange it.