I agree about acceleration Trigg...someone in another thread mentioned how he thinks D9s are flown bolder than Ponies in the MA...not sure about that, but if it is so, the reason would be that a D9 can slow down and fool around playing the E game with a Spit or something, but can also REGAIN its speed in a reasonable time frame when 2-3 of the Spit's buddies come in.
Right now about the only thing the P-51 does better than the D9 in the MA is beat D9s like a red-headed stepchild in turn-fights...that is, P-51 is the worse turner vrs. 90% of the other aircraft, whereas for the Dora its 99.9%. Dora has the better weight-to-power ratio at MA alts, cannon package, roll rate, and here is the clincher, D9 is an incredibly steady gun platform vrs. the slight odd "twitchy" feeling Ponies and Jugs have for some reason.
Now if the AHII Pony actually turned somewhat better than say, the Typhoon/Tempest, (as the Brits say it did), that would be enough of a margin to put the Mustang head and shoulders above the Dora IMO.