Urban is a bit young, Sinise a bit old. I too prefer the distinct difference in age between the characters of Kirk and Bones.
Urban will be great though. (I think Sinise would have been cool also)
I am going to speculate that Urban will be played as older then Kirk in this movie. Academy together deosn't mean that Bones isn't older. Damn'it he's a doctor!
It's all gonna come down to the story. Will it be any good? Thats the real question.
"I'll break out of this zoo somehow and get to you. Is your blood red like ours? I'm gonna find out. "-Captain Christopher Pike