I can't speak to the specific speakers. On the other hand I own Klipsch, Polk and Emotiva speakers. I highly recommend Emotiva towers (I have T1s). The Polks I have are low-end, TSi100s and formerly a CS10. The Klipsch are RB51 IIs and R41-Ms. Clarity and detail of the higher frequencies are especially important to me. The Klipsch have clarity. The Polks really don't -- the tweeters suck, although midrange is pleasant. The Emotivas have both clarity and effervescent detail. Due to limited space for it, I'm running an RSL CG23 between the Emotivas, and it blends perfectly. The Klipsch as surrounds and heights are close but not perfect. When I had the Polks in the mix, they really didn't fit well.
Now, does Polk use better tweeters in their better systems? I hope so. It's not purely a matter of ribbon tweeters (Emotiva) vs. horn (Klipsch) vs. dome -- because the RSL's dome is as precise as the Emotiva's ribbons. The Klipsch horns, for whatever reason, are great at bell-like tones, but come up a just a bit short on more complex harmonics. It looks to me like Klipsch uses the same tweeters across its models, but I'm only guessing from appearance. I did have Polks in a car back when that were pleasing, but the system driving them was hardly hi-fi.