It should be more effecient with the input output voltage close to the same. It is a buck converter though, I would imagine its still pretty effecient with a higher input than output. If the input is 60v and you need 30v at 10 amps. Thats about 60v at 5amps needed on the input side of the DPS5020. That’s cruising speed for 60v 15 amp supply.
Having the higher input voltage puts less strain on the power supply if your operating it using almost half the needed voltage out…