Hell opens its gates by itself. I can't remember an instance where either a Zanpakutou or a Quincy sent a soul to Hell. (But then again I'm only up to the start of the Wadenreich arc.)
I think the simplest solution for the Purifying Arrow dilemma is to make it more exhausting to use. It is, after all, more complex to develop.
EDIT: I also wholeheartedly approve of the idea of MV making Miya's mom a villain.