as you probably realize the polk will not be as good as the klipsch... the klipsch is much more powerful and will probably be cleaner and crispper... also the sub in the polk system is much smaller... its 165 watt i believe i saw whereas the sub-10 is 450 watts i believe... i have the sub-10 and love it... my speakers are all yamaha but i did seriously look at the quintet II and loved how they sounded and looked but just could not find them for the price i wanted... so basically i would personally go with klipsch... i am more of a klipsch fan over polk to begin with although polk does make some good stuff... although as many in this forum has said go and listen to them and see which you like better... if this is a system you really want to have some boom to it i would definatly go with klipsch... but like i said listen to them and see which you like best! hope this helps!
If you could get your ears on them, that would be best but that often sucks when it comes to in-store demos.
I don't believe that their is a major compromise in sound quality between the two products. The frequency range is very similar when you factor in the K subwoofer. I believe the soundstage will be larger with the Klipsch due to the design of the actual loudspeaker. It's an MTM array and designed large and ported. The Polk system takes a different approach and may be more directional depending on your enviroment.
At this stage of subwoofer, wpc doesn't mean much and both will be just fine.
I like the soft dome of the Polk over the Klipsch but the K has the advantage in regards to room coverage as a package. Surrounds don't matter at all in this example.
Hey, good luck and let us know where you go.
Mark