Given the steepness of the Old Trail, the only real advantage is when you are returning to the Portal and going down the trail. I don't see any advantage in going up it when you are heading up the trail at the beginning of your hike.
CaT
I agree. We used it one year when the creek levels were high to avoid the crossings. Otherwise, you do not really save that much distance since you still have to walk to and from the trailhead. You just get to flat pavement quicker going down the old trail.
