Talon, I like the Jug too, but come on, let's be honest.
First and foremost, the Jugs didn't have the range the P-51 had until the P-47N came out. The P-47Ds simply couldn't do the same missions the P-51 could.
Second, I just did a quick look at the P-51 B and Ds vs. the 47Ds performance up to 30K in game. Basically, there is little or no performance advantage to the Jug before the M/N below 30K, and performance disadvantage below 20K. Of course, that doesn't take into account things like Robert Johnson's hot-rod, but its a good measuring stick. If we want to compare a very-late war upgrade like the P-47M/N to a Mustang, then it is most properly compared to the P-51H.
Third, one of the reasons I often fly a Jug instead of a Pony in AHII is that here is little or no maneuverability disadvantage in flying the Jug, indeed, in pure turning radius and slow handling, the Jug has it over the Pony in our game. This simply does not mesh with real-life assessments of the aircraft by both Allied and Axis pilots. Awhile back, I posted the commentary of a Luftwaffe pilot who also tested captured Allied aircraft, his words were something along the lines of "The P-47 was not so bad because the 109 could out-climb and out-turn it, the P-51 was another matter."
For very long range escorts and as a dogfighter below 25-30K, the Mustang was indeed a step forward. For dominating at very high altitudes and as a rugged jabo platform, the Jug was indeed the right choice. The Mustang probably does get too much of the press, but that doesn't mean it wasn't the right plane at the right time.