Here's my thoughts:
The Alderaan Explosion looks great. However I'd suggest not putting any PT characters in there and rather using a pure scenery shot from the ending of Ep III. It's too much of a distraction and as such it kinda lessens the impact of this very powerful scene.
Also if scene as a whole, it is kinda a cheap way of killing off characters that weren't used in the later trilogy anymore.
The Star Trek scenes look awesome! That really would be amazing.
Regarding the light sabers, I think the colours are still a little too weak.
The lasers from the fighters take some getting used to, but they look decent. Never bothered me on the official DVDs though.
Two scenes I didn't like were: The Falcon flying into the hangar. The glow has a very smooth edge and looks a bit unnatural.
And the tractor beam scene with the Matrix colours. Dunno, just didn't dig em.
Other than that, it's absolutely awesome! Think this will be THE edit to go with.