Well said fellas, and that is pretty much what I said in Paragraph 3:
If the relative infrequencies of your own breedings are such that you can't get all of them done while he's there (or, again, while he's being campaigned), then if you really value your stud's unique/superior qualities over everything else you've seen, then by all means try to preserve them any way you can. If not through breeding to him "now," then making sure you have his sperm available when you are.
Point well taken,
Jack