the weak hand doesn't have to reach across the body so far, and the shirt isnt' as hard to "clear" in this position. In fact,if you inhale as you draw,and lean BACK a bit as you draw, you don't have to actually GRAB the hung out t shirt (also faster than a "tailed" button up shirt, less likely to tangle up your draw) You can just "brush" the shirttail up high enough to clear the gun butt. This results in a faster, "cleaner' grab of a 2 handed stance from ccw.