Part of the reason New Horizons is going so fast is to reach Pluto in "only" ten years. A Hohmann transfer (which you would need to make a ballistic capture) would take about 124 years just to reach Pluto.
The article led me to believe you would avoid a Hohmann transfer with ballistic capture by flying it into a similar orbit and letting the planet slowly creep up on the probe and pull it into orbit. Am I misreading that?
You're cutting the final burn but you're still pulling roughly the same maneuver, by taking an orbit that peaks at about the same altitude as pluto, and that is a slow orbit.
