Re: Dipole - bipole??
Dipole has two speakers that fire out of phase (one pushes while the other pulls). This creates a null directly in front of the middle of the speaker.
Bipole has two speakers that fire in phase. This helps to create a "diffuse" sound, but does not create a null.
As to which might be better is up to your taste and your room. Dipoles only tend to have a good effect when you have good speaker placement options. If you have an odd shaped room or are very limited in where you can put your speakers I would hesitate to recommend dipoles.