What I do like about the English System is the ability of holding a note, or chord and be moving the bellows in and out create a vibrato effect, it is of course possible on the Duet, but as yet I have never heard a player use it. The wonderful Tommy Elliott was a master of this style of playing switching from single note to high speed vibrato.He also used this method to perfection playing the miniature. This is not to be confused with "Bellows Shake" that can be done on the Anglo.
I have a video of Tommy playing I must see if he uses the little finger rest.
Al