Whoa - look at the time. I just completely lost track of this thread. Petalas, for best results, you want the front three speakers to match, as sound is frequently panned across them, and you don't want timbre changes as the sound moves from speaker to speaker. Sound is also panned front to back, so surround speakers that match reasonably well with the fronts are also desirable, but I'd start with getting the primary sound sources (your front speakers) to match, and upgrade the rears as budget and time allow.

So, if you like the Klipsch's, see if you can get either an identical speaker for use as center speaker, or a center channel speaker from the same line -- horn loaded speakers like your Klipsch's sound different than speakers with cone drivers like your Polk. If you like the Polk better, start with that. But I've found five matched speakers of moderate quality usually present a more cohesive, pleasing soundstage than five unmatched speakers that are otherwise superior.

-avi