Hi Ronny
That's a really detailed answer but basically if you look at the research that has been done on the way the ear/brain mechanism works it does not hear 'comb-filtering' in the way that the measuring microphones do.
The problem with using a larger tweeter is the off-axis frequency response starts to narrow very quickly as you go up in frequency. The Bryston speaker design is based on as wide and even an 'on and off axis' frequency response as current technology allows.
james