In the book "Hornet Country", which details the F-18 in Australian service, it describes how test pilots mentioned that the Mirage 2000 had "the most beautiful handling characteristics of any performance aircraft I have ever flown", and this was in comparison to the F-18, F-16, and of course the Mirage III. So it stands to reason that the Mirage in DCS handles so easily, because it's the same in real life.