Hello Christa,
You are some what right,however both paths are very complex in there own right and of course you put "Black" in front of any thing of a spiritual nature and its considered bad right away.
I my self come from a Black Tantric background,how ever ive never referred to it as such nor heard it used as such with that tidal.
But some things that needs to be clarified yes some of these powers/Siddhis can be used to harm,or to protect..once one has archived some of these ability's it is like a sword it can be used to destroy or cut some thing down to build some thing,the power is what you use if for.
That is the basic version of that but it also gets more complex with what Devi/Demons gods goddess or energys in the universe you work with.
I also not call it a sub group but its own group with in its self.
Chris