Audiokinesis is correct.
Berner, A dipole is special because it radiates in a figure 8 pattern. It radiates very little to the sides. A bipole is omnidirectional radiating in a circular pattern. The dipole limits early reflections in the room. If the dipole is a line source the only reflections will be to the front (early) and rear (late) walls. No the side walls, the ceiling or the floor. The early reflection off the front wall is easy to control above 250 Hz. Below 100 Hz were things get critical the best way to deal is with subwoofers right up against the wall and in corners. That way the primary sound wave an first reflection are identical. All this makes room treatment easy. The resultant system will have relatively smooth bass response throughout the room and superior imaging. I am not prone to superlatives but the imaging is vastly superior in all dimensions. Getting a bipole to perform like this is difficult, maybe even impossible. It would require the right room, extensive room treatment and clever set up. Since I am dumb I'll go with the dipole every time:)
Mike