The advantage is more space to mount gear like a bike computer, a GPS, an inclinometer, heart rate monitor, fascia for the motor control when you fit one, even something which requires as little linear space as a circumrotary twist-bell or Cateye's little normal-appearing bell which requires only about 10mm to mount because it stands enough proud of the bar to allow for other controls to be mounted under it..
Measure carefully. Julian makes an excellent point. When I first went over to North Road bars, I though, Ooh, lots of straight space for grips and switches before the bend: who could possibly want more? A couple of years later I needed much more. Now I can't remember a year in which I required less handlebar space than the year before, and most of the additions require to be close enough to operate without removing my hands from the grips.
