Move to Live
The photo of Carteach0 that I chose to illustrate this post with ironically is one that he uses to illustrate what not to do. Movement and balance are as individual as people. Some shooters will be dangerous as Plaxico if they cross their feet. Others can move with the grace of Marcus and Karen Hilton doing the Tango. I personally do not feel concerned about crossing my feet while moving. Of course, I am not moving and shooting on packed snow and ice like Carteach0. I also have a background in ballroom dance. Oddly, I would advise anyone interested in developing footwork independent of torso movement to take ballroom dancing. I never thought about it before, but there it is. Ballroom dancing is all about complex integrated footwork with control of the torso.
One other thought..... Training to move laterally is good. Diagonally is better. But the best way to train by far is to move towards cover. Handguns do not have an infinite supply of ammunition. When used in self defense, a handgun often expends it's ammunition at an alarming rate. An extra magazine or speedloader is handy, to be sure, but one must remember that it is far better to reload behind cover than reload in the open. We will fight as we train. If we do not train to move towards cover we may very well find ourselves reloading in the open when we least want to.
I suppose I should say it, although it should be apparent without my doing so..... If a shooter decides to train with movement, they should advance slowly, and practice movement while dry firing first. If they have laser grips on their handgun, it can be an effective tool to evaluate exactly how well they are making progress. Safety is paramount.