I think After the Fall is actually bringing up the actual question of who is a "champion" in Angel. Gunn was always an ordinary man living in the world of demons and fighting it for revenge and because, well, he's human. But he's not anymore and he continues to fight for good, according to him, for what? Revenge or because he wants to? If he actually does good, does it matter? And does it mean more if he does it while being a soulless monster?
Angel, on the other hand, was a monster given a soul and it hurt him like hell. He had all the strength of a vampire but was forced to deal with his inner demons. He fought good because he felt guilty, because he wanted to redeem himself in his own eyes. And now he's human, ostensibly redeemed from being a monster, but still he fights. He fights like he doesn't have to worry about his newfound weakness. Like he's not mortal. Because he wants to continue the fight for good and save humanity.
Meanwhile, Spike has all the strength of a vampire plus the soul, but he's still a selfish git. He sits as a Lord of LA drinking blood from a fountain and having gaggles of women around him and, yeah, he helps Illyria deal and the underground human resistance surreptitiously, but he doesn't engage himself directly and avoids confrontation.
I dunno. I'm more interested in the character development than keeping the characters static because that's how they were.
Also, The Buffy/Satsu thing is growing on me the more I think about it. Buffy is lonely and stressed. Buffy is surrounded by girls who idolize her and even love her. Satsu is more of an equal to Buffy than most of the rest and...she needed release. I think it was irresponsible of her, but it's not an inconceivable act.