It turns out that this was a big fuss over nothing. All the batteries, whether KR or CN, have at least the rated capacity according to Dell. The issue seems to be that the "info" software misinterprets the data from the battery, or perhaps the battery is incorrectly reporting the maximum capacity. In practical terms this doesn't seem to matter.
I regret that I got sucked into this and had Dell send me a replacement battery. My testing shows that both the old and new one deliver the rated "hours" (both are the KR batteries which the batteryinfo tool reports as being 24WH.)