I suspect that some of the 'old' tunings are purely because of the auditorium.
I noticed, because I have an excellent tuner on the computer, that the louder/harder you play, the flatter the note gets! It makes sense (to me) that the Salvation Army instruments, being intended for playing outdoors and along with brass instruments, are tuned sharp to compensate for this.
This is a personal theory, and I'm just putting it up to be shot at.
Chris.