I play DH on her as support all the time.
In my experience, to hit the Electrocute, you HAVE to his Q+E+Auto or R in order to land it, and it just doesn't particularly work as fluidly with her burst pattern since plants have a pretty hard time triggering it.
DH, on the other hand, can be collected by the plants excessively easily, and I can't tell you how many times I've spawned a plant under a tower for that quick bite and the DH stack before the tower nails it. It makes her ult extremely vicious when you crank out your E+W+R combo, and it just overall makes your poke extremely deadly.