- In my opinion, the biggest problem of the I-16 in AH is its very poor directional stability which, based on my testing, is due to the excessive gyroscopic precession of it's prop. At low speed the aircraft can just depart sideways as the gyroscopic yaw overcomes the aerodynamic force of the vertical stabilizer which doesn't seem accurate at all regarding practically any prop driven aircraft really. This makes the aircraft a handful to fly through which a lot of its maneuvering potential is lost.
http://bbs.hitechcreations.com/smf/index.php/topic,291191.msg3703387.html#msg3703387- Another issue is its rather poor prop efficiency especially below best climb speed (for example being slow on the top of loop). There was some talk when I-16 was initially introduced and Hitech adjusted the prop efficiency back then. Considering the shape of the fuselage and the shape of the prop, I'm sure this is pretty accurate.
- While two cannons makes for a decent armament they have very short clips of 90 rounds each. Small amount of ammo combined with poor directional stability deprives a lot of lethality from the armament.
The I-16 is crippled in terms of range.
If you set away 10 minutes for combat purposes, the I-16 has a range of about 70 miles (at full military power) on deck while the B-239 has about 150 miles.
While I agree that the range with internal fuel is easily poorest of any fighter in the game, with drop tanks, one can fly a very similar mission profile as the Brewster with 50% fuel. IE. short distance between fields; you go in, do your thing and leave as the ammo is gone.

Of course just talking about what I'm used to do personally. It's a very very rare occasion I take more than 50% fuel to Brewster.