Until the Revel F328Be and the S7T are measured in the same exact manner and listen to side by side it's hard to know which a listener might prefer. The Revel F328Be sounds absolutely great to me. I can't imagine wanting much more. I can easily use them without sub for music listening. Based on the S7T roll off at 80Hz a sub would most likely be required with it.
As far as distortion, Amir's review sums it up nicely for the F328Be.
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Tbh at this price range you should get a sub because not only the placement of stereo speakers completely bonkers for subbass but intermodulation distortion is nasty in a full range speaker, no matter how low the harmonic distortion of the drivers is.