I remember reading something about this on the gw-warmaster group, so I thought I'd bring it up.
It is a nasty thing to do, and I am not sure how it work out on the battlefield. For example, you might end up parking 4-5 units in initiative charge range of a very peeved enemy. And this is the kind of trick you do ONCE, because after that, the opponent will not let you do it again.
Overall, I think it is a cheap trick myself. I like the idea of the chracters seeing the enemy coming, and so get out of the way. This makes sense as an explanation.
And no, I will not try this in game play.