Don't forget that Freddie Hubbard played cornet on Herbie Hancock's "Emperian Isles" (one of the greatest albums from that period I think). Here is a quote of him talking about it from an interview:
I’ve been playing the flugelhorn about four years, and now I can play it better than the trumpet, because it’s much easier to play. But I had a little old cornet, made back in about nineteen–twenty–something—a short, stubby instrument; one like Louis used to play, with the round back. It had a beautiful, real mellow sound; it was in between a cornet and a trumpet so small that I could do a lot of things on it that I couldn’t do on the trumpet. I used it on an album with Herbie Hancock and when I heard the playback, I said: “Wow—did I do all those things?” It was almost like I had complete control of this little horn. It wasn’t like the cornet they play today; it was much fatter in the back.
The entire interview can be read at:
Freddie Hubbard 2