Danny:-
But who is going to gainsay the (late) Eric Brown, the most famous test pilot of all time ? Our esteemed friend "Chugalug" will remember all this .
Indeed I do Danny, as I do your revelation of the incidence of the MkIV being some 4 degrees whereas its predecessors were set at zero. Thus the MkIV was not capable of an accurate 90 degree dive for bombing purposes, adding dive bomber to all the other uses it was useless at! I'm sure that must be what Winkle Brown condemned, just as you have done ofttimes.
All of which rather begs the question of the Stuka's angle of incidence. Was that also zero? It didn't seem to adopt the typical nose high attitude in Straight and Level as the Vengeance did in contemporary pics. I suspect that it was also a compromise like the MkIV, but perhaps somewhat less so. Certainly Luftwaffe tactics were to use a steep dive rather than a vertical one. That seemed to work well enough for their purposes, given a benign state of air superiority of course.