How much travel you get out of the RD also depends on the relationship of the cassette to the derailleur hanger. Some frames have a hanger that's so thick that a spacer is needed behind the cassette, just to get the cogs far enough to the right. Campy recommends 7-9mm from the face of the axle. I recently put a .75mm spacer behind the 11 speed cassette on a powertap wheel because the RD would barely travel far enough to the left.