Hey Eric,
I have to admit, I wasn't disappointed about the Flashback scene being where it was in the movie, I kind of liked that, I think it adds to the poignancy of the fight scene more than if it had already been shown in the first part of the movie. In the book the scene suprises you, because you never really knew for sure how intimate they really were on the mountain, but in the movie we have TS2.
What I do agree on is that after TS2 the time on the mountain is gone before you know it, and that really disappointed me, and I know that Ang Lee must've meant by that that the good times are over before you know it, but hell, I never really got the time to get into the it's just the two of us in paradise" feeling.
It's just like that they left out the "That's one a the two things I need right now..." scene that I absolutely adored in the movie and that, in my opinion, should definitely have been in the movie because it would have shown that the deep love they feel is still there, which would have softened the blow of the fight scene. The omission of that scene I regard as the biggest flaw of the movie.