I wouldn't bother myself, but that's just how I am.

If you're unhappy in any way w/ the current MC, or think it might be showing signs of age and have future problems, than now would be the time to change it. They're very similar cars, even by 5th gen civic standards, so I don't see why the MC would differ, but at the same time I don't see why the Si would come with drums in back either so... I know why they did it, but I guess I don't approve.

edit: :goodjob: on the change btw, the convenience alone when changing pads/shoes is well worth the trouble IMO, especially if you get a good deal on the new calipers, rotors, etc.