I think one of the most overlooked strengths of Batgirl's vortex is the number of ways she has to start it. Even when Frost was at her peak, you still knew exactly what she was trying to do, and she only had a couple of ways to get it started.
However for Batgirl, you have to worry about: 6 frame Flying Bat (MB), a quick overhead with deceptive range, one of the game's better lows, random cross-up d2's, her jumping 2 (and random ambiguous crossup j2's in the Sonic Fox setups), MB teleport, random Bola (even on trade), etc.. Not to mention the nonsense she gets into in pressure when she starts staggering strings and whatnot. It's an endless list.
This alone makes her vortex that much more potent. A random button from wherever gives her a chance of putting you in the loop.