In AH the airplanes fly entirely too smooth. There's no jump, jitter or imperfection inherit in the various planes. Not to mention, some planes seem to defy gravity and physics and it's entirely too easy to stall fight.
Try stall fighting in IL-2, a much better overall and detailed game, it's much more difficult to both recover and maintain stability in otherwise unstable airplanes at lower speeds. And the phrase 'speed is life' means a lot more in that game.
Il-2 uses a generic flight model with tweaks for an aircraft's speeds and climb rates. It does not model any of the airframe specific effects from speed that Aces High does. To claim that Il-2's flight model is even equal, let alone superior is absurd.
The bombers in this game are a joke, far too easy to fly and with the ability to potentially aim 6 different gun turrets in a formation on the same area is just silly. The fact is if you lost control of your giant b-17 or b-24, or tried to make some silly turn, you would fall right out of the sky. The b-24 in particular was very difficult to fly and required constant correction and attention. Not to mention they are way faster than they should be especially at lower alts.
The B-17 was known for sedate flying. You seem to fall prey to the "The pilots of WWII aircraft were gods whose like shall never be seen again!" line of reasoning. These things were being flown successfully by 20 year olds. That isn't to dismiss their skill, but to ward off the idea that these aircraft were incredibly hard to fly. The B-24 did have some problems at altitude.
I like Ah2, it's fun, but I'd be careful calling it a simulator, particularly if the planes aren't modeled right! It's seems like propaganda really, the axis airplanes are nerfed. The 109 could drop flaps at 300 true and it wouldn't do justice to the 190 to say it was better than the P-47. It OUTCLASSED the p-47. P-51 pilots wouldn't engage Ki-84's, they were too dangerous and at some alts was FASTER. And the German guns were not as difficult to use as they are in this game, the 30mm was only 10% slower than the .50 post-muzzle, over distance I can understand the drop but not after 200 yards. The C205 is a good plane in this game, but like the 109, 190 and some Japanese planes, isn't right. It was a monster of an airplane in real life.
Use a source other than Il-2. Your specific claims are flat out wrong. The P-47 broke the back of the Luftwaffe in the West, not bad for a fighter that was outclassed by everything it faced, no? Oh, it wasn't outclassed, sorry. The Ki-84 was faster than the P-51D at some altitudes in post war tests using 100 octane fuel that the Japanese did not have, they had, being generous, 87 octane. The Ki-84 in AH is modeled on Japanese flight data. The Ki-84 in Il-2 is modeled on post war US tests using 100 octane. I've never heard that P-51s wouldn't engage Ki-84s and their respective records in WWII don't support that claim. The MK108's and Browning .50's muzzle velocities are well documented, your claim that they were close to the same is flat out wrong. The C.205 was good, it was not a monster as you claim.
All of the planes in this game after all were excellent in their own right, at least in life. Plus some of them are completely backwards in this game. The Spit16 was a high alt fighter and the clipped wings didn't allow it to turn very well. In life, the Spit14 was the better turn fighter. They're backwards. The p47 outclasses the 190 in this game. That's backwards too. And the Brewster is probably the most outrageous of them all. If it was really that good, do you think it would have been replaced by the Wildcat? Or the P40? And how is it that the P-51B's 4 .50's don't seem nearly as powerful as the Brew's?
The Spitfire Mk XVI was most definitely not a high altitude fighter and I have no idea why you think it was. Its Merlin 266 had a critical altitude of about 18,000ft. The Spitfire Mk XIV was a high altitude fighter, its Griffon 65 having a critical altitude of about 27,000ft. Both of those facts are modeled correctly in Aces High. The Spitfire Mk XIV, having the heavy Griffon engine, is significantly heavier than the Merlin Spitfires. Adding weight does not improve turning capability. The Brewster in AH is the B-239 used by the Finns, not the F2A3 Buffalo used by the Marines at Midway, the B-239 has wing loading of about 25lbs per sq.ft, the F2A3 has wing loading of about 34.5lbs per sq.ft. It is very slow, slower than the F4F and much slower than the P-40s. As to its guns, the code for a given gun exists in only one place in the game and all aircraft using that gun call the same code, so sayeth HiTech. They are the same guns and your style with each aircraft probably explains why you find the Brewster's guns better.
http://www.wwiiaircraftperformance.org/
That is a great site that many of us use as a go to reference. It supports everything I've said here. Note, for example, how Il-2's roll rates don't match the NACA roll rate chart on that site.