I'm not sure Ativan is a step below Xanax. Maybe Klonopin could be considered a step below both. When I saw the pdoc who helped me the most I was taking Ativan. She prescribed Klonopin instead. It was much more effective for me but I didn't have panic attacks per se.
As the members above stated addiction is always a possibility with benzodiazepines.
I think of "as needed" as a kind of security blanket rather than a "go to."