I'll chip in w/my own verdict:
If we're talking strictly movie Rorschach, I give Mills more of a chance than if he were up against all-round-portrayal Rorschach(so yeah, including Before Watchmen - don't hate me, some of it was actually pretty darn good).
But either way, once Walter gets an idea of just how hardcore an opponent Bryan is, he's definitely not gonna hold back.
So I go with Rorschach, but in a purely-physical scrap Bryan will make him work for the win. Should Bryan be packing heat though, different outcome.