I marched 3 seasons (88-90) playing 2-valve G bugles. I can tell you right now that I can hear the difference between a line playing G horns vs B flat horns. As others have already stated, G horns had a much brighter tone thanks to the overtones they could produce. B flat hornlines sound "duller" to my ears. G horns also have a more power. I remember the SCV shaking the stands in Cincinnati back in '88 during their victory encore. I don't get that sense of power with modern lines. Some say that B flat horns have better intonation. Maybe so, but I preferred the rawer, more powerful sounds for G horns.