I stick to the D-25. Better speed over the D-11 and accerate better over the D-40.
I have chased down "N" in the D-25 and take them out. Some people just do not fly them right. "M" is one Jug that I just cannot match. To powerful against the D-25.
The D-25 cannot out accelerate the D-40 if the pilot knows what he's doing. Its the same airframe with a more powerful engine in the D-40. If you've chased down an N in the D-25, then the N pilot was either out of WEP, or not paying attention, as it possesses a whopping 600 more HP on WEP than the D-25, while only weighing in a bit heavier (relatively speaking).
Personally, I'd rank them, in order of performance: P-47M, P-47N, P-47D40, P-47D25, P-47D11 and in that order of air-to-air combat ability as well. The D11 accelerates like a true pig. People perceive an instantaneous turn advantage in the D11 because overall, it usually weighs in much less that the later models. Before the M came out, I believe the N was the best air-to-air Jug platform, just because most MA fights usually evolve into 1v1 low-speed turn fights where the high power of the N makes it perform best. Especially once it gets light, as the wingloading on the N (more wing area than the D models) starts approaching fully loaded Spitfire numbers (say at 1/4 tank of fuel and half ammo or less). If you can stay in the fight with 800 rounds total and an 1/8th of a tank of fuel, the N can get pretty sprightly. Now that the M is available, it is the air-to-air king of the Jugs, and handily so. The weight of a D model with the power of an N model--that's the best of both worlds. Its still a big, heavy aircraft, which is why it doesn't carry a perk--that, and the fights in-game typically don't occur at 28,000 feet like they did over Europe. If the game constantly put you into combat at those altitudes, the Jug-M would be a perk plane because it would be one of the best performers in the game, behind the Me-262, Me-163, and arguably tied or better than the Ta-152 (and perhaps the Spit 14).
As for high-altitude combat, the ability of the Jug series to make basically sea level power at 30,000 feet is what makes it so deadly. Thank the designers for that turbo system instead of a supercharger--a indicator of its design use being as an interceptor rather than a pursuit fighter. But, fighting at that altitude requires a completely different skill set than most AH2 pilots possess from in-game experience, as you must be more patient, more methodical, and keep speed on the plane at the detriment of maneuvering. The energy equations at those altitudes are completely different than they are at typical AH altitudes, and will humble you quickly if you don't adjust your flying technique.
I mark the whole series except for the N and M as some of the most difficult aircraft to master in-game, which is why Bluekitty, Yucca, and some of those folks were so impressive to watch in the D models...
