They do movie sound VERY VERY well. And other stuff too. My best possible solution would be to score another pair of K-Horns for the rears. That and the "C-Horn" (that's what I'm calling a knock-off of a K-Horn "top" with K-55M mid, K-401 Horn and K-77 tweeter - AL-3 x-over) my bud is putting together for me - would be the way to go, wouldn't it?
But for financial and spousal considerations I think a pair of Cornwalls would be just dandy back there. As to the concerns from another poster about not having a bass bin on the "C-Horn", this is a going to be a dedicated HT set-up. When I use the K-Horns for music I wouldn't be turning on the other three amps/pre-amps. Then it would be all about two channel sound. And later, when we're watching a movie and using the new speaker for center channel output (which is primarily vocals and some background music) I think it will be fine. I do have my Yamaha powered sub in the center of the room so it will be "kinda" ghosting for the C-Horn.
Keep the critiques and suggestions coming! This is fun. BTW, I have some pics of my HT set-up, but I'm not smart enough to post them here. Any suggestions?
John