Tootsall---
I'd have to say 'yes' to your last question about efficiency. It doesn't mean that Bachs are a bad horn, it's just that they have their place.
I know what Larry is talking about when he mentions the problems groups had when most everybody is playing Bachs and someone shows up with a high efficiency horn----or even a horn that sounds a lot different. My community band has nine horns and six of them are Bachs. The six Bachs are playing the 1st and 2nd books. The third books are playing a King 600 (big, solid core of sound), my Director cornet and a Bundy. We do our best to blend, but everybody knows where we are because we sound so different from the Bachs.
Anyway, I like feedback in addition to projection. What I see as a good horn is one that resonates well and a horn that does that usually has good feedback. What I also notice about these horns is that they 'vibrate' or 'resonate' well and you can feel this. You can sense when the horn is vibrating well and that seems to be when the horn is playing at it's best. I rely on that feeling quite a bit as our trumpet section is right in front of the percussion and there are times when I can't hear myself play. I rely on the vibrations and my experience to guess that I'm playing on the right note.
That's my two cents worth.................
Bill