I agree that this thread has lost its course so I'll put it back on track... kinda.
Instead of having 'absolutes' how about add some random variability to the game. I think its safe to say that no to engines performed identically, and that being said maybe we add some degree of randomness to things, maybe your plane doesn't do exactly 405mph at 20k but instead 398 or 407, etc... This could be applied to engine over heats as well. Maybe just because your radiator was hit, your engine doesn't die exactly when it 130C (I think that's what the gauge is at), or maybe the time it takes to red line out is slightly different. Also, to add something like the occasional gun jams or engine failure would increase the 'realistic' aspect of the game. For example, I have read that some 109 pilots didn't like the gondolas because in high 'G' maneuvers the linkage chain had a tendency to fail, etc...
Another, thing would be if you could mark a plane as yours, then you could fly this plane until you lost it by being shot down, crashing, etc...