Superman is manageable, IMO. He has few options when knocked down as Bane can simply d2 both of them (microstep into d2xxgrab serves as a really effective option select), 11 can be used to challenge Superman pressing buttons after breath, and Superman does not have very good armor breaking outside of his trait. Just have to manage your trait with his in this MU.
Also, if Superman can't wake up, he can't cancel into trait. It's definitely a tough MU, but no worse than 6-4, IMO. Bane has legitimate options in this MU, while against Beetle or Wonder Woman he has close to none.
Batman used to be Bane's worst MU a couple patches back, but the quantitative nerfs to his meter build and trait rebuild helped far more than I could have envisioned. Still losing, but playable now.