HD is a fast spell and actually got uses in WoE relatively compare to Thunderstorm... if a sage is to try mobbing, HD is generally the superior choice unless there is elemental advantages.
I don't know, I have mage points typically to waste for this, as I don't care to grab SC, I have a hard time actually fitting in HD 5 in the grander schemes of my build, but by all means feel free to grab HD if you are able to. HD does have less cast delay btw, its one of the few spammable sage moves you got.
HD overall doesn't have as many elemental advantages in many places, so that's why TS can almost be more advantageous to some too.