You right, It doesn't have input or output delay so it can be catspammable. If you have high mod+ capacity, It will be 1 to 2 shot and so smooth on gameplay.
0:39 fun fact : if u search in pg3d wiki. Harpy does more damage cuz dual anger does 46 to body and 66 to head but if u use wears and wears, harpy does 76 damage so harpy does more damage than dual anger