As an aerodynamicist myself, I found the new AIM-120 behaviour to be quite unrealistic. I mostly agree with 85th_Maverick 's points but I would like to add a possible explanation about the first real life aim-120 kill, which seems to match the current AIM-120 model on DCS.
The rocket motor was still burning at the time of impact, meaning that some of the centripetal force needed to turn is actually given by the motor, and not just the fins. The CFD study I found online about the new aim-120 for DCS states that the maximum AOA is 30 degrees, its thrust would be 16700 N and its weight around 150 kg (at launch); while using this data it appears obvious that as soon as 30 degrees AOA is attainable (you don't need to be in steady state flight for this), the missile could turn at 50 g's!!! Which is even above the airframe limit. This means that the real missiles steer mostly in the first second of flight, this is why the real missile hit that MIG-25, not because it had God-level lift. I have personally witnessed (in game) an AIM-120 pulling 14 g's at mach 1.2 while losing speed almost at the same rate as an afterburning fighter. THIS IS INSANE.