Haven't heard Greg's speakers but intimately familiar with Cornwalls and other things Klipsch.
It's my experience that three things will improve the performance of Klipsch horn speakers, especially the larger offerings.
Sit far enough away for the drivers to integrate. Horns are not near field, or even mid field speakers.
Do NOT toe the speakers enough so that they are firing directly at you. Even the newer speakers like the CW IV sound better when the axis crosses well behind your head.
SET amps bring out the best in Klipsch speakers that are efficient enough to accommodate them. A good 300B amp with stout transformers and power supplies will handle that 15" driver of the Cornwall with no problems.
. Modern klipsch speakers have advanced quite a bit over their predecessors, some of which could run you from the room. Even as good as the new ones are, they aren't for everyone.