DM will always be a problem/issue/source for debate...
All pilots wants to have guns that will kill quickly, be it smoke/fire/departing parts/PKs ... yet the same pilots will also want to be able to survive a hail of bullets fired at and hitting their aircraft - to continue the fight, or to limp home... yeah - conflict - oh well, there's a war on, so a conflict fits in nicely
As for DM modeling: The challenge for the developers is to somehow create a situation that results into an in game balance. It can never be based on pure technical data - back then there was no air crash investigation, no black boxes - most of the pilots shot down either never knew what killed them, or never took the time to figure out what caliber of gun hit where and did what kind of damage. When hit good and still alive, a pilot would try and assess whether he could get home, get over to friendly territory, or simply bail out as fast as possible.
This is where it shows it's just a game - main driving force here should be play ability - not realism, as that would mean game-over way too quickly and often, ie. no fun at all!
Sure, we call out there's a war on, but in the end it's just a game on!