It is puzzling that most martial artists always talks about putting 70% of body weight on the hind leg, and 30% on the front leg. And while sliding the front leg forward, the hind leg is still stationary. Obviously this gives the opponent a chance to attack at this instance.
I feel that to perfect this, we need to put all the body weight at the hind leg, hence the front leg is very flexible. And while moving, the hind leg is the power house, and the distance between front and hind leg need not change at all.
Nevertheless, it would be a very difficult task to do. More perfection is required.