One thing I've notice about your kicking, kangaroo, is that it could have a bigger effect on the rest of the body. There are times when he makes a powerful kick, but his body just keeps doing what it was doing as if nothing big was happening. try having the center joint follow the kick just a bit, but make sure to move his other joints to compensate for the movement.
EDIT: (this post references the combo, not the ball kick. the ball kick was rather nice.)
Well, when you've read as much of this thread as I have...
I remember your first post. a juggling anim.