Will continues to do well. We had his 2 week checkup, and it turns out that he has grown 2 inches since birth (in length, not girth; they didn't measure girth, and it might have grown 2 inches as well). He's gained a pound as well. We need not worry about him.
He spends most of his evenings eating constantly.
During the days, he sleeps, eats, or is mauled by his sisters.
Great fun is had by all.