Final addendum (for now):
I am also beginning to wonder if a 3 captain group is not superior to a 2 captain version for an extreme DPS set up. The reason is that with 2 captains, you still have a chance to have your perimeter units go outside of the Rally coverage, whereas this is far less likely with 3. I just stumbled on this as I started training my 2nd “Fearless” captain to replace his predecessor who is merely “Brave.”
