Listening Areas in Open Concept Home

My stereo setup is currently in a large living room/dining room (29' X14' rectangle) which has hardwood floors and a large archway on each side of the room.  The archway leads to the foyer on one side which opens to upstairs and downstairs and the kitchen area on the other side.  My system Rotel 1582 Amp 200 wpc with Martin Logan motion 40s and Dynamo 700 Sub.  Speakers are on the short wall playing into the length of the room.  The sound travels throughout much of the house.  I'm not unhappy with performance but often wonder how this setup would sound in a more confined space.  I plan to move the entire setup to my carpeted family room on the lower level which is smaller (21x14) and more irregular shape.  Since the speakers must go on the long wall the listening position will be much closer.  There is no door at the stair so the room is still not closed but more closed than the current location.  Should I be concerned about overpowering the new room or ending up with boomy/muddy base especially with wall to wall carpet.  Bass in the current room is nice and tight.  Other concerns?  The new room also has a brick fireplace directly beside where the right speaker will reside and an encased A/C vent which drops from the ceiling right behind the listening area.