Mu's meter should really only be used for RC and CA. Only use a super if it'll kill or you have 4 steins behind them and they have no anti-projectile stuff that will mess with your pressure after mirror. She does have an easy as to combo into astral though (3C astral, air hit J2C dash 3C astral, and in corner air hit j2c straight astral)
Just remember if you intend to DP and RC to make it safe, hit 5C after, since you can combo from DP 5C 6C into a short combo. If you're going to ikutachi to get out of corner off this, imo do ikutachi 2B 6A SoD.