I currently have 2 PSB Image B6's as fronts and an SVS PB-1000 Subwoofer. I'm looking to get surrounds next and was wondering would it be better to get a pair of Image B6's to match the fronts or get Image S5's, bipole speakers?
Ideally, gaming wants all 5 channels to be exactly the same. They aren't doing any fancy mixing, they are simply positioning audio at 360 degrees and reducing down to X number of channels. As such, 5 matching speakers is ideal, that way a gunshot in any location sounds exactly the same regardless of which sound-hole it's coming out of. Bi-poles's will diffuse the rear channels creating a wider area of coverage and larger sweetspot at the expense of locational accuracy.
Bi-poles were great for the ProLogic I days, but don't have much of a place in a modern home theater unless you are doing something odd like two-level seating or something.
Then yes, angle the speakers to the halfway point between the chair and bed, then run MultEQ setup with the mic in all 6 positions starting at that midway point, then the center of the chair, center of the bed, then a couple points where your head ends up when you lay on the bed while watching a movie.