My setup is: BL8000 front and BL4 as rear, connected to the Avant DD module. The BL4's are hanging upside down on the wall mounts at about 220 cm above the floorlevel. I think they are good enough in the surround-setup for watching DVD's with 5.1 sound. Disadvantage: the direction of the BL4 is fixed in the wall mount, you cannot direct it to the center of the room.
When used as extra speakers when listening to music (SPEAKER4) you notice the difference in quality, I always take care the the BL8000's produce the loudest sound.
In general: I'm satisfied with it. When money was not an issue I think I'll should use a pair of BL3 for a better balanced use when playing music.