The use of dipole or mono depends on your room and speaker placement. I find that if you have a large room and can place your listening chair in the center of the room, away from walls, then you can get good sound with direct radiating monos behind the listening position.
You indicate that you have to use side speaker placement on the walls. I find that this is not ideal for direct radiating monos and that dipoles are preferable (this is the highly debated THX preferred setup). Direct firing speakers to the sides of the listener, with no additional rear speakers, gives poor envelopment and no soundstage behind the listener. Dipoles give a better surround experience and rear effects are more convincing. The B&W SCM8 THX dipoles were the best (the only home theater speakers to ever be on the Stereophile recommended components list that I know of).
You indicate that you have to use side speaker placement on the walls. I find that this is not ideal for direct radiating monos and that dipoles are preferable (this is the highly debated THX preferred setup). Direct firing speakers to the sides of the listener, with no additional rear speakers, gives poor envelopment and no soundstage behind the listener. Dipoles give a better surround experience and rear effects are more convincing. The B&W SCM8 THX dipoles were the best (the only home theater speakers to ever be on the Stereophile recommended components list that I know of).