Small adjustments to the headjoint to allow it to fit will not hurt anything. The B foot will not give better response in the 3rd octave, but depressing the low B key will improve response of altissimo C.
Both the Sankyo and the Powell are fine flutes. You should choose the one you prefer.
Toby
Both the Sankyo and the Powell are fine flutes. You should choose the one you prefer.
Toby