Just to be clear, when I say authenticity is paramount I do mean across all 3 modes.
Even in BoP arcade mode you can't out turn planes that you can't out turn in sim/real. So the FM does apply in Arcade, but the other factors balance it out.
As long as they get the basic FM's right then the game will work in all modes (it very nearly does in BoP) and still be credible.
For me it has to have the obvious stuff like ,Relative Top speed, rate of climb, combat flaps, engine characteristics (Realistic and above), roll rate , diving capabilities (Realistic and above), all as close as possible.
I really don't mind outdiving a Spitfire in a 190 at 800mph(Arcade) or 400 mph (Sim), as long as I can do it