Belle: If they brought back Kirsten Storms to play Belle, that would be awesome! I loved her as Belle. That one other actress who only played her for a few weeks was pretty good, too, but I can't remember her name. Martha Madison, definately not. Nothing against the actress, but I just didn't like they way Belle was portrayed when played by Madison. Admittedly, though, this probably has more to do with how the character was written.
Mimi: If she were written the right way, yes. However, if Mimi came back, I would want Rex and Cassie to come back as well.
Shawn-D: If portrayed by Jason Cook, yes. He and Kirsten Storms worked well together as Shawn-D and Belle. Brandon Beemer...not so much. Again, nothing against the actor himself, I just prefer Jason Cook in the role of Shawn-D. I'm with the viewers that say Jason Cook is the only Shawn-D and Kirsten Storms is the only Belle.
While it would be great if these three characters came back, I just hope that if and when they come back, they will be portrayed the right way.