Generally, as an Nd-Fe-B materials maximum energy product goes up, Hci goes down. When and why should I care?
You should care if the magnet is going to be exposed to elevated temperature(above 150 °F/ 65 °C), if the magnets will be in repulsion, or if the magnets will go into quadrature or Halbach assemblies. You should care because low Hci magnets will irreversibly lose a lot of magnetic strength. Usually this can be recovered by remagnetizing, but if they are in a complicated assembly, you might have to take it apart.
