Thanks for all the feedback!
Few things:

MrInsaneA:
I'll only replace the Imperial March cue IF I find a more powerful version. But for now, it'll stay. So don't you worry!

On the topic of the Federation music in the march scene, I initially thought as you do - but then I realized it's not actually Federation music. It's really only "Clone Wars" music, and doesn't seem to be anybody's particular theme. It just sounds like the Federation theme. However, I would love to replace the front end of that song either way.
I was thinking about using the track from John Williams' score to "Midway" titled "Burning Carriers" for the front-end of that scene, and then fade to the Imperial March. But... I think I would need more talent with music mixing to make it sound good. We'll see.