I was on the crossfire for a year or two and just last summer picked up the K2 outlaw. I was worried I would have to bring both skis on ski trips, but I won't have any need for the crossfires out west, now.
Besides the obvious width difference, I think the outlaw is just a better ski overall. You may find it hard to believe, but I can carve better on the outlaws. I don't know why. Of course, they also feel alot more stable all over the mountain.
The obvious: they are so much better in chopped up snow and on steep terrain.
I have heard the chief is more of a dedicated powder ski. If you like K2, I would try the outlaw or seth before the chief for all mountain skiing.