RE isolated scores and this project:
There are already so many audio mixes included that adding more would begin to seriously compromise the video quality.
Since ESB and ROTJ will include fewer mixes than Star Wars, though, it may be feasible for them. But I'd rather all three remain consistent - either they all have isolated scores, or none of them, and I wouldn't add any more mixes to Star Wars for fear of hurting the video.
Just my two cents.