Hi Vinssen,

Allow me to say that the most important specification of a home theater is its total size relative to the number of listening seats.  A small room cannot support a large audience regardless of its shape; square or rectangular.  A larger room not only accommodates a larger audience but it provides more flexibility to proper layout the acoustical framework.  The acoustical framework includes the speakers, subwoofers, and seats.

My assumption is that your are asking about cutting a larger square room down to make it a properly proportioned rectangle.  The answer is, that I prefer a larger square to a smaller rectangle.  The key to making the system in the square room successful is the proper design and calibration.  The issue of a square room creating coincident modes is eliminated by understanding how to properly place seats, subwoofers, and speakers.  This is true despite the fact that I prefer a rectangular room.