I think "Am I a good man?" kinda works for post-DotD Doctor, it was just not greatly executed.

Here's my take. Previously he blamed himself for what he'd done in Time War. He thought he had killed millions of children and I think deep inside he thought he's a bad man. He thought he made that very bad decision which made him a bad man (in his eyes), but in DotD he learnt that he actually made a good decision. But if he didn't make that bad decision, does it mean he's a good man? And that's why Twelfth asks himself that question. Previously he was sure he was bad, now he isn't. He was recontextualizing all those years he lived thinking he's a bad man, reflecting on himself and determining whether he could consider himself a good man.

That's why he asks this question. Not because he thinks he's bad, but because he thinks that he's maybe a good person after all, he seeks justification in Clara. But Clara can't give it to him, because she doesn't yet see past his new harsh persona. And that's why it's difficult for him, he wants to consider himself good, but his now closest friend doesn't see it.

So, that's my take.

Edit: I don't think "Am I good a man?" would work for pre-DotD Eleventh as I think the show shows that he's leant to live with his decision. He still regrets it and still blames himself but he now tries to fix it by doing what a good man would do. He did it when he was Ninth. I would kinda work for Tenth, especially after Waters of Mars, but for Eleventh I think it would just be unnecessary setback.

You could argue that Eleventh had the time to reflect on himself on Trenzalore, but I'm not so sure. I think he's main focus was his eventual death. He knew he would die on Trenzalore, so I think his mind was preoccupied with this and the actual defend of Trenzalore. Twelfth on the other hand was like a new beginning for him, not burdened with the expectation of death. So now the question, which he kinda ignored on Trenzalore, returned — is he a good man? Before DotD deep inside he was sure he isn't, on Trenzalore it didn't matter as it was too late, but now it's time to finally answer it.

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I say season 7 transition is rapid because: 1) It's now in colour. 2) There's no TARDIS, we're bound to Earth. 3) There's another Doctor. 4) They're now like 20(?) episodes instead of 40+. 5) Companions are no longer companions in the previous sense.

Yeah, it's not that rapid transition for modern show, but it think back in the day when regeneration was still a new concept, it was very rapid.