The major difference that seperates Klipsch from the rest is the quality. Their connections, wiring, parts, etc are top of the line and built to last, withstand loud decibels and major auditory abuse. Z560's aren't manufactured to that quality and won't last as long.
Klipsch are expensive, but worth every penny. I bought a pair of Klipsch LaScala speakers for my stereo in 1979 and they still kick ass and rattle windows. I've gotten Yamaha's, Denon's and Infinity speakers along the way since '79 but none have ever been able to match the sound of these incredible speakers.
Z560s do sound incredible. My BF got them and they do sound awesome...until I turn on my Klipsch in the next room. Blows them away.