I understand it on the old, level playing field. I am still learning how to do it on end-game Rey without any end game gear or abilities of my own. I have the heavy hitters, but they usually leave Rey with a sliver of health. She has so far proven to be very slippery.
Adding the next gear level, she is just barely out of reach of a high probability kill with RG guarding her. And when she gets buffed by QGJ and/or Phasma in round two, she has just enough firepower to take out your own DPS. Even with full health, she will reliably ohko low protection glass cannons. Just lights out.
She is an interesting challenge for me, right now. I am not at all interested in a nerf. As I said, I believe she will be fairly meh once the new purple jewelry starts to trickle through the arena. I will be trying to land a debuff on her, soon as I gear up the right toon. If that fails, I will try bringing in an AOE.