"from your replies I gather that breaking the uke's balance is the crucial issue here."
Kind of clear you don't understand kuzushi or its benefits. This statement alone, and certainly in concert with the technique centrism, indicates your level of understanding.
It is a rather sad state of affairs that Kathryn has to state the obvious in the comment just above, for it is not obvious, apparently, to all.
Actually, Aikido constitutes a smaller part of my martial arts background. What is a rather sad state of affairs is that I can't ask what may be obvious to advanced practitioners without inviting this sort of comment. I came to this forum to learn things.