generally when you are going for sq you don't wan't multiple drivers playing the same frequencies. That's why most people going for SQ just have a 2-way or 3-way front stage with no rear fill (some people like rear fill some don't, but I'm not getting into that). When you have multiple drivers playing the same thing it messes up your staging/imaging and causes problems with phasing. If you are just trying to make it louder this won't be as much as a concern, but if you're really going for sq these are things that will cause you big problems.