I've had the both the PBR + Kappa and the BT set up and on the road, it's not even a fair fight. I was not a fan of the PBR at all. I had the same Kappas connected to a RZ42000d and then a PPI 900.4 and can honestly say that with the better amps those speakers get incredibly loud and clear. A tad bright but loud. I'd say the Cerwin B2 is a better option over the PBR these days in terms of SQ (and the same price). This would be a killer set up for the price.

What the 7.1's have over the kappas is low end. It's a fuller sound that still sounds good at hwy volumes.