[tomaz]

A bit late I guess but after reading most of these pages I'll add my two cents of, hopefully, practical suggestions and not pie in the sky stuff.......

For SP;
1. As mentioned, random mechanical problems forcing a return to base, a forced pause at base(e.g. you are forced to sit in your aircraft [for 60 seconds or more?]until you get a message that your plane is fixed), then being allowed to take off again to try to catch up, locate your mates and finish your mission. The point being if you have to RTB early, then what?
2a. Airfield "life". It doesn't have to be human characters walking around (although that would certainly be nice) but some vehicles moving around or planes being towed and airfield/hangar ambient sounds/noise beyond just birds singing etc. I always try to liven up the home base for my co-op group so that it seems that activity is going on around you and we're not the only ones there. A 'wounded' aircraft from a previous mission crash landing while I wait for takeoff. My point being that little things like that add to the immersion. An empty and sterile base where you and the other planes are the only "active" things is kinda dull. Not much point in having a ton of ground objects/people on your airfield (or any airfield) that don't DO anything. A little bit of eye/ear candy can make a big difference IMHO.
2b. Along the same lines, if coming back to base all shot up and making a tense landing or crash landing, hearing or seeing an ambulance and fire truck heading my way would add some immersion too.
3. Adaptive or updating radio chatter on enemy activity/location. This has been mentioned before on these pages so I won't belabour the point. Il2 1946 radio chatter will respond (sometimes) if you ask for a vector etc but it would be nice if you didn't always have to ask so to speak.
4. Taxiiing for takeoff instead of the neat line astern takeoff routine (I believe you've already addressed that from beta videos I've seen).
5. An AI "witness" to a kill in the post-mission debrief. Guncams weren't available early in the BoB so witnesses were very important for claims.
6. Crater damage to the runway that takes a while to repair and can damage your aircraft (I believe this is also part of your sim already but thought I'd mention it).
7. While I assume a lot of "briefings" would/should be along the lines of... "211 SQUADRON SCRAMBLE!!!!" followed by a radio update in the air en route to your intercept, more deliberate briefings should allow for the insertion of recce photos if applicable or even a recce film (that's stretching things at this late stage, I know, LOL). Perhaps in a later iteration of SOW.
8. I agree with the comments on the bailout sequence/animation/routine. A first person view would be preferred - being able to look around, check your canopy, right up to the thud/grunt of hitting the ground. Some steering of the chute would be cool to try and avoid landing in a river or whatever.(i.e. simulate the pulling on one of the risers).
9. As I'm sure has been mentioned elsewhere, the ground control radio traffic should be looked at, if it hasn't already. The IL2 1946 ground control radio traffic, specifically in the landing process, for example is incredibly repetitive and boring to the point that I simply switch off the AI chatter (especially online).