[unreasonable]

If any changes are made to this I hope it is through some scaleablity in the mission builders rather than an overall "hidden" variable like in IL2 where flak was absurdly overmodelled.

Until someone does some empirical tests on the effectiveness of CoD's flak I would hestitate to judge - early war AA defenses were rather ineffective, eg:

"In Dec alone (1940) German flak forces accounted for 31 aircraft destroyed, at an average expenditure of 7,058 heavy flak rounds and 20,604 light flak rounds per aircraft". (source "Flak: German anti-aircraft defenses, 1914-1945" E.B. Westermann a book I recommend highly to anyone interested in the subject).

This period is one of no ground fighting (like the BoB) - so reasonably representative of what the BoB AA might have achieved against high level raids. Obviously low level ground attacks against heavily defended point targets like the Sedan bridgehead were much more dangerous than attacking RAF bases. While the BoB raids were in daylight and many RAF raids at night, the British AA was technically behind the Germans at this stage of the war, so the results are probably similar.

None of this is meant to underestimate how frightening it must have been to bomb a target with heavy AA defenses, especially when you had to do it over and over again.