
So it has an extra fuel tank tucked in behind the pilot (scary but true, these guys really did fly them like this, and my hat is off to anyone that did fly them). So if you want Spitfire type dogfighting capabilities, set your fuel level to 40% and that should eliminate the nasty stall characteristics due to the changed CoG.
If you are flying escort missions however, you'll want every last drop of that precious fuel (and this is what the Mustang was for...).
Remember the Mustang had range that no other fighter could really match, the Spitfire was without a doubt the best short range fighter ever made, but the Mustang could go all the way to Germany and back.
Both fabulous aircraft, but comparing them is like comparing a Land Rover and a Ferrari, both are marvelous in their specific enviroment, but chalk and cheese otherwise inspite of their having wings and a single engine apiece.
Ozzy