I stopped feeding the nucs on August 23rd. Dead brood started showing up on the landing board of nuc #1 on September 3rd, a sign of malnutrition.
Clearly, these nucs are finicky about feeding – too much syrup, and they prepare to swarm. Too little, and they starve. I did a quick inspection of the nucs, and although there was some brood, the frames were very light and dry; they reminded me of potato chips. The syrup jars went back on today.