I asked this question on the BOSE user forum - the expert stated:
That's a great question; every room provides a different challenge and a new opportunity to learn more about acoustics. From what you've explained, it sounds that the dancers might be absorbing the sound that is trying to get to the back of the room. I personally try to avoid using a satellite speaker due to phasing and delay issues. If you feel this is the only way to get sound to the end, try to have someone at the back at the room during sound check to listen and adjust for delay or phasing issues.