I'd turn on the heel to shift from horse to front. No part of my foot leaves the ground. It took a while to be able to do it smoothly, which probably turns alot of people off.
For those that would turn on the ball, how do you keep your back heel from moving further away from your target? You could lose a several inches of reach like that?
Stand in a front stance with your fist touching the wall, perfect stance, perfect posture. Shift into a horse stance, now shifting back into a front stance on the balls of your feet, can you still touch the wall? Are you leaning more than you did before? Try shifting back and forth several times, how far away from the wall are you now?