The P-51 was a fine a/c which did its job well, however it is often overrated. The P-51 wasn't individually anything special, being out-performed by a good number of German fighters. That having been said the P-51 was a responsive aircraft at the speeds where most of the dogfighting was taking place by 43-45, speeds where the differences in wing-loading between fighters suddenly became irrelevant as neither pilot nor aircraft could take the maximum loads which the lift permitted. This is exactly why the Fw-190 really handed it to the Spitfire in dogfights and often by outturning it.