The great Morton Debate !
Well as a confirmed member of the Morton fan club I was urged to reply to this intersting post. It must be remembered that although Ernst Benge was asking Clarke about a switch there were many others who did in fact stay with the cornet when deciding between the two instruments. For instance Bix Beiderbeck played on a cornet in a period where trumpet was dominating in Jazz. There are however others who prefer the cornet in Jazz, for instance Ruby Braff (I think).
The tone and melody arguments about cornet players only being the ones that can play a slow melodies, when compared to their trumpet counterparts is a rather weak argument. Here are some names who have swapped at times to the trumpet from cornet :- Harry Mortimer, Rod Franks and Maurice Murphy. Hearing them play a slow melody is as good as hearing a cornet player play a slow melody. The texture of both is quite obviously different, we have in banding perhaps a misconceived idea that trumpet players can't play soft, mushy tunes, that I'm afraid is completely wrong. In many ways I think being able to play lyrically on a trumpet is harder than playing one on the cornet.
Both instruments have specific attributes that can in different contexts make either one better than the other or both perform approximately the same. I've often heard people say that "cornet players" that play too straight and clinical sound like "trumpet players" and it is rare that I have heard that a trumpet player is ever said to sound like a cornet player. The only difference between the two, as I can see, is the opportunities that are quite frequently given to trumpet players, are not available for cornet players ( i.e cornets feature in bands, wind bands, military bands, in Jazz sometimes, very rarely in orchestras, where as trumpeters are often seen in all the above plus pit orchestras).
Well thats what I think anyway..