Hi Jessie,
Generally, Axioms QS surrounds have a pleasing timbral match to Paradigm Studio reference models (I have a number of different Paradigms of varying age and prices, including the Studio Reference 20s and ADP surrounds). The QS8s have larger woofers and 1-inch voice-coils on the tweeters (compared to 1/2-inch voice coils on the QS4s) hence the 8's have better power handling and greater bass extension--more "punch" if you will.
The controversy over multipolar vs. direct-radiating at the back for 6.1 or 7.1 continues. There are no hard rules here, but I prefer multipolar for a timbral match to my surrounds at the sides and because of the enhanced envelopment with little or no loss of directional acuity. The QS models also blend well with the Paradigm ADP surrounds.
Others prefer direct radiators.
Regards,
