Neither speaker will work well in this room you have a number of problems, one you have a square room, two you have a smaller sized room for large speakers to be positioned and not to over load the room with bass.
MBL's and for that matter any omni only work well in larger rooms where they can be moved far away from room boundaries.
The Sarastro is a very fine loudspeaker but one which will have too much bass for that room.