Depending upon where your Main Listening Position is within the room, and the shape of the room (closed on 4 sides or open to another room), the SB1000 may be enough. My room is 13.5' x 19' x 7.3' and open on the left rear side of the 19' dimension about 2/3's to an 12.5' x 10' dining area.
Under those conditions I have a dead spot of little bass in the right rear corner and need a second sub because I can find a more effective place for the one. In retrospect I should have gotten an SB2000 first and added a second. As it stands now if I upgrade to a pair of SB2000's before mid November this year I'll get full credit from SVS for the one SB1000 I've already bought. That's cool, I just hope I can save up the required funds.