IIRC i saw Erich Hartman say in a video that he think that the p-51 was better then a bf-109g above 5km,and the opposite below 5km.Anyway in the low alt fights we have in MP the p-51 feel very slugish,which might represent the correct behavior of the plane.
Anyway i just wanted to put here links for a very interesting youtube videos from Greg's Airplanes and Automobiles channel,that might be related to op post.