Regarding harmonic content and THD over 120% for switching power supply currents. Please let us not forget that the 'linear' power supplies of yesteryear were series regulators fed by TR packs. And the TR part is a transformer driving a full-wave bridge followed by a capacitor input filter.
THD was perhaps just a little better as a result of tranformer magnetizing current, but the even harmonics were worse. And there were the ferro-resonant designs with almost square wave current, and line-frequency phase control with outrageous 2nd harmonic content. This is not new news. It is rather like automobile HC emissions were not a problem in 1906 compared to methane from the horses....
