Originally Posted by AeroGut

With regard to your specific question about the length of the housing, the reason it doesn't have the big curve that you're used to seeing is that this somewhat new design (meaning within the last 15 years) orients the cable end roughly downward and rearward at the point of attachment to the derailleur. Most other derailleur designs have the cable end pointing forward and slightly down at the point of attachment, so the cable has to bend quite a bit farther around from the starting position of pointing straight rearward on the chainstay. To make that additional bend without introducing a tight radius kink, the path of the cable had to include a large curve. Some earlier designs addressed this same problem by using a pulley wheel to achieve a tight-radius bend rather than reorienting the cable attachment and lever arm.