Please forgive me if anyone is tired of the whole monopole vs. dipole surrounds debate. Ultimately I do believe it comes down to one's preference, so what follows will just be my personal observations and experiences with both types of speakers. For the past year or so I've been using a pair of Polk f/x300i dipole/bipole surrounds, trying them in different locations and in both modes. Ultimately what seemed to suit my room best was dipole mode, mounted on the side walls 8.5 feet up and in line with the listening position. Even though I found what I think is the optimal location I was still very curious how a pair of monopoles would sound, situated in their respective optimal locations. Since my main speakers are JBL S38s and an S-Center I was also curious whether timbre matched surrounds would make a difference in the overall experience. I've tried out pair of JBL S26s, placed 5.5 feet up, on the side walls, a couple feet behind the listening position and facing into the room (per the Dolby recommendations). After listening to my usual reference films (Star Wars Episode 1, The Matrix and Heat) I can certainly see the appeal of monopoles and might even say I prefer them to the dipoles. The surround field is much tighter but by sacrificing the expansiveness of the dipoles there's a gain in clarity of effects. Scenes like the pod race in Phantom Menace have a stronger directional force in front-to-back pans, creating a more dynamic viewing experience. Diffuse sounds are not as diminished as I would have thought and ultimately I think the combination of diffusion and directionality is more balanced with monopoles. Having direct radiating surrounds is therefore not as distracting as I thought they would be. Having a pair of surrounds timbre matched to my fronts also helps with the z-axis pans. The Polks always sounded brighter than the JBLs, so I was never quite happy with that obvious shift. I will of course listen to the same scenes again, many times, as well as try other material. I welcome any comments you might have on the subject!