+1^^
For most cases, the caged bearing setup from the factories are more than adequate.
Going with loose balls/additional bearings in the races will definitely be a plus, in terms of ultimate smoothness and maybe just a little bit more durability because of the loads being spread around to more bearings, but the difference in both departments will most likely be imperceptible to almost all of us...... Just keep the headset well maintained and adjusted and it should last just as long and feel just as good.....