I agree with BillJ's post, except for one thing. The Spock scream bothers me, and I just realized why.
The build up of the reversed-parallel scene was almost right.
I think it would have worked better if Spock let the tension build in his face exactly like Shatner did in TWOK. But instead of the scream, he should have remained silent and then went on to beat the batcrap out of Khan. After his speech about choosing not to feel, releasing all the pent up emotion at that moment seemed a little soon.
Saving the outburst for later would have made it perfect.
EDIT: Now that I think about it, mirroring Shatner's "collapse" on his side of the wall would have been better. Then the Khan ass-whooping.
I could go with your edit, but I didn't really have a problem with the scream because I saw it as Spock finally giving in to the emotion and lashing out like a primal scream (his mom, his planet, and now the person Spock Prime told him would be an important part of his life, and with whom he'd do great things, is struck down prematurely). So in context, it worked for me. But it's fair to say it suffered (and maybe was cheapened) a bit for some by being identified with the Kirk scream, especially since that scream has become something of a joke over time.
Also, remember, at the time Spock didn't know if Khan was alive or dead. That is, he didn't know there was an ass to whip, yet.