Hard to compare with how it's set up. I only have one center channel 8351. It seems to go louder, but not as deep, but that could also be me "hearing" what I expect with the specs which I looked at many times before getting the 8351B.
I wish there were cheap automatic software to volume level multiple speakers. I'd love to host a shootout between the 8260, 8351B, 8331, Kali IN-8 V2, and Kali IN-5... Maybe cut the bass off around 50hz and see who wins, and move up and down and left and right to see how the dispersion is. I think I even have a black sheer cloth to obscure things and enough stands to put them all on the same level.