You have mostly missed the point. It is well made fairly accurate film ...
But the most significant thing is not picture quality or whether the 109s are exactly right, or even the precise historical accuracy, but that you should get the DVD version with the intended Walton film score.
I have just watched it with William Walton's music [for the nth. time], and the film certainly carries a bigger punch for the minimalist approach, musically speaking. Goodwin was a superb film-score composer, but unfortunately his compositional finger-prints are massive, and show a certain repition between various films.
Walton's score is a complete enhancement of the film. Laurence Olivier threatened to remove his name from the cast unless a portion of Walton's music was retained. The Battle in the Air was kept and is the musical high-light of the otherwise Goodwin music as released in the cinema. In the Walton version, it comes as a cumulation of the musical tension already built up.
G