GREAT THREAD LARRY!!!!
Gets so many thoughts roling around in my head. Going to comment on one aspect of your post at a time, just to keep "my"head clear.
You said ("can't say both") in asking would a player want to hear them selves so well that it effects the projection of a horn, what the audience hears .... NO ... "I" would not.
"The Audience" is who's paying / listening / or we could even say the 'microphone' is an audience in a recorded secssion. The sound must project / be heard / get out there / get on tape. So ... all other factors being equal, consistant and controlable ... of the two, my priority is projection out front.
