I also play both IL-2 and AH regularly, but of the two more time is devoted to AH.
IL-2 is obviously very good in graphical features, and the gunnery model is simply the most convincing I've seen yet.
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However, the view system is a head banger. I play with 'hands-on-stick-and-throttle' configuration(not necessarily meaning a HOTAS stick), and I control the stick with right hand, manage plane functions with left. Obviously I'm not giving up one of my hands by confining it to a mouse-look. I use the hat keys and what can I say, the head movement is slow. Too slow.
Also, the head position is very uncomfortable, and can't frankly figure out why 1C:Maddox did not implement customizable head positions as in AH. Sweat Jesious, the 'neck-brace' head movement is something from the mid-1990's!!!!
Because of this, some planes practically fly around with about half of the forward screen covered with struts and metals. Frickin' frustrating. The zoom is also set in three levels, and cannot be customized.
Also, one the most frustrating thing about IL-2 is the 'mushiness' in controls. Ofcourse, about 70% of the reason is in the insanely delicate stick calibration. If it is even most slightly wrong, the pitch control is wild. But the rest of the 30% is inherent in the flight model. Trim is way too sensitive, and wrong trim configuration means nose bounces grandeuer. Also, the yaw axis is also incredibly unstable compared to AH. Few slight rolls left and right, and the aim is thrown off.
Another big problem, is the super high E-loss tendency.
Anybody who plays both AH and IL-2 can feel this. The average speed they fly around and fight in IL-2, even in 1944 planes, is around 300~400kph. Make a few turns and the speed drops under 300kph. Translated in AH yard figures, the planes fight around 185~250mph, and a few moves will drag your plane down to 100~150mph level.
At first, I thought the compression/stiff controls factor was strange in IL-2. Also, I thought the black out was too lenient. Then I realized that in IL-2, planes rarely, if ever, get to fly speeds over 600kph(370mph) so basically there can't be a black out or stiff controls. Yak-9Us and Bf109G-6/AS fight at speeds the F4F-4 and A6M2 would have fought in the War.
Overshoots are almost impossible because the E-loss is so high that a plane dives from behind from alt, he sees a plane breaking away, just lowers throttle and engage flaps and you get a dive-break working even better than the SBDs and Ju87 in AH.
So basically, the concept of ACM in IL-2, is coming in from alt, and just saddling behind the other guy. No matter how high, how fast you come in, lower the throttle and you can just saddle up.
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Bascially, the IL-2 FM, is like flying around in 70% throttle in AH.
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Other than that, the features are nice. I hear they redoing FM and E-retention/loss factors in "Forgotten Battles".