You might want to go for the Klipsch, or another 12", for a room that size. I have a room of a similar size, though it has a 25' cathedral ceiling lined with tongue-in-groove cedar and opens to a loft area upstairs, along with a flagstone fireplace in the center of that. The living room is like some Canadian hunting lodge plopped down in the middle of Florida (Rumor is that some guy from Alaska designed and built it over the course of a few years.) I had a 10" KSW-10 that just didn't cut it. I'm now using a RSW-12 that has two 12" subs in it. It does the job, and I'm happy with it, though a 15" sub is probably what is truly required considering the volume.
The ideal thing would be to find a B&M place that sells a sub at a good price. Take it home. Try it out. And if it doesn't satisfy trade it in for a better or bigger one until you find the one that's right to your ear. Getting a good price is fine. Paying a little more for the insurance of satisfaction is even better.