Yeah, played some with Nemesis, Jill, and Leon.
They definitely feel a bit stronger than Heather and Pyramid Head sadly. Granted, survivors are ultimately just skins once leveled up, as they can share skills.
I also think the zombies might get some re-tuning for Nemesis. They act totally independent of you, but they help more than you think. I have had zombies grab survivors when I **** up a chase, and you can kill them if need be to increase your mutation level.
And you can troll by letting a survivor escape after you pick them up by standing right next to a zombie. The zombie will instantly jump on them, downing them for you to pick them up again lol.