Well, to me it's not all so black and white. You see, I'm Italian and if anything else, Angel reminds me of a character from one of the most famous Italian novels (if not the most famous), Alessandro Manzoni's I promessi sposi (The Betrothed). This character is the Innominato (the Unnamed) and he used to be this really evil guy only to find god halfway thought the novel and undergoing a radical change, going from Big Bad to a force of good in search of redemption. Angel does the same thing: unlike Spike, he is not one for half measures, he is either the ultimate evil (Angelus) or a great hero. It may well be that the similarities in Angel and the Innominato's journey is due to the Catholics origins of both characters. And the aforementioned search for redemption, which is a very Chaotic thing and no, you're right, there isn't a "secret number you can hit where good balances out bad", that's the point of atonement, you're never really done with it, that's why the Shanshu prophecy doesn't really matter in the end and even defeats the purpose, I mean, it helped Angel find hope at the beginning of his journey but now he is wiser and tougher and he doesn't need that crutch any more. To me that's character development.
Anyway, what I meant to say, Angel is still acting as this grandiose hero in season 5. If he can't beat W&H he'll still try to bring the house down with him inside, no half-measures. Which is something I find to be really coherent with his character.

I also think the redemption theme finds some resonance in season 5, only it's mostly through Spike, who, as he always does, acts like a mirror to Angel's character. Think about "Soul Purpose", with Lindsey taking on Doyle's name in an attempt to convince Spike that he is the one mentioned in the Shanshu Prophecy and him and Spike basically reacting the plot of the pilot of Ats. Which, yes, it's in stark contrast with Angel's situation in the first half of the series, who's now helping the helpless on a large scale and in a more detached way, no longer on a down to heart/one by one approach, and he's a bit adrift, without Connor, surrounded by friends with false memories and being without Cordelia and having lost his link to the PTB (the real ones, not Jasmine). A link he will regain in You're Welcome, which will lead to Angel finding his purpose again and to NFA.

And wow, the more I think about season 5 the more I discover a fondness for it I didn't suspect I had stored in me. Must be the Devil's Advocate in me. More likely, I'm just feeling really nostalgic for Ats, I really have to do a rewatch sooner rather than later. But, yes, season 3/4 are still my favorite ones... No, scratch that, I just found out why picking a favorite season is so hard: it's exactly because Angel's journey is so interconnected through the seasons. Something gets foreshadowed in one season only to reach it's development in another, picking one means wronging the other ones. It's like choosing one of your hands over the other: how can you do that? :D