The acoustical problem with pulling out the barrel is related to the gap left between the barrel socket walls and the tenon walls. In a "perfect" setup the bore is unaltered when the barrel is fully pushed in. When you pull it out the gap there is enormous per perspective. The further you pull it out the larger the "square crevass" that is created which surrounds the entire bore. This crevass is what affects the throat notes so much. The throat toneholes are the closest extensively used notes. Plus the throat tones are not perfect to begin with due to design. A FullBoehm Bb sounds alot different than a throat note Bb. With the CSG design that gap made by pulling out the barrel is pushed further away from the throat notes thus affecting them less. Of course the best solution is to have various barrels of various lengths to prevent having to create that gap.