Here's another few more thoughts to inject some life and variety into the game:
Currently, the only thing really differentiating one aircraft from another is the raw performance data. Top speed, climb, acceleration, stall behavior, guns, etc. Other than that, operationally all of the aircraft are more or less the same. They all have the same subsystems and controls. Fuel management, flaps, trim, prop speed, etc. are all the same. On the one hand, sure, it makes it easier to hop from plane to plane. But you lose some of the aircraft's unique character.
For example: The Wildcats all had manually-operated gear, with a crank that required being turned 29 times to raise and lower the gear. In AH, it's done with the push of a button. While that may seem like a minor thing, other aircraft had more significant features.
Case in point: The N1K2-J had automatic combat flaps. The F4U and F6F had "blow up" flaps; rather than being locked in place, the flaps on the Corsair and Hellcat were controlled by a spring. The first two notches would automatically "blow up" if deployed above a certain airspeed, but then would drop again once the aircraft was below the speed again. And of course, there's the lead-computing sight used on later Mustangs.
So here's a comprehensive suggestion for remodeling of aircraft systems:
1) Implement complex engine management, in the following manner:
1a) Make this an "Opt-In" setting, like Stall Limiter and Engine Governor. If CEM is enabled, players have direct control over fuel mixture, propeller pitch, and cowl, radiator, and oil cooler flap positions, and supercharger speed. Players that leave CEM off can fly like they always have, but as with the Stall Limiter and Engine Governor, it prevents them from pushing the envelope. Players using CEM may be able to squeeze a few extra HP out of their engine by tweaking the mixture, or add a few feet per minute to their rate of climb by adjusting their propeller pitch, or eke out a few mph by closing their cowl flaps, or get an extra few miles of range with the right settings. All of this would come at the risk of over-revving the propeller, or overheating the engine (oh yeah, add engine overheats. Although the implementation should be less heavy-handed than in Il-2).
1b) Model management per aircraft. IE the Corsairs had four settings: Idle/Cutoff, Auto Lean, Auto Rich, and Emergency Rich (technically only three, because the latter was permanently disabled) so would not have fully manual mixture. While German aircraft would have their automatic propeller pitch (this would need to be distinguished in some manner from disabling CEM).
2) Combined with the above, consider remodeling WEP management, as not all aircraft had it as it's currently presented. IE, the Corsairs simply increased the throttle beyond a stop above 100% to engage water injection.
3) Implement some of the unique aircraft features. Rather than a "Gear Up/Down," have a "crank" key for the Wildcat's landing gear that needs to be pressed so many times. Add automatic flaps on the N1K2, allow the F4U and F6F to "set and forget" up two notches of flaps. Implement the K-19 LCOS, perhaps as a Perk option for the P-51D and other late-war aircraft that carried them.
3a) Perhaps include some common field mods not otherwise represented as another perk option.
4) Remove ammunition counters for planes that didn't have them (which was pretty much anything but the Germans, IIRC).
5) Remove trim axes from aircraft that didn't have them (IIRC, some aircraft didn't have trim for every control axis)
6) Oh, and add clickable Virtual Cockpits. Not completely relevant to this, but it would be cool, and would help VR guys flailing about for the keyboard because they forgot to map one particular function they suddenly need. :-P