Based on general inability to use it correctly or reasonably I'm removing that tag.
Hide-Vote will be staying, and joining it at some point will be a hide-opinion that works similarly but based on you having not chosen a or for the post containing it.
Existing uses of hide-reply may or may not remain hidden for a while until the system realizes they don't work any more. It seems 50/50 on whether it removes it or leaves it hidden. I may have to uninstall and reinstall the feature with my changes to make it fully clean up.