I agree, I would not put DT under the "faux" blanket. They have earned their stripes as a genuine progressive band. But admitting that does not mean I have to enjoy their music. As for more progressive than SX? I'm not so sure. As far as innovations to the genre and unique tendencies...I'd say SX has the edge. Nobody was playing anything like The Divine Wings of Tragedy when it came out, whereas DT's arguably most innovative album Images and Words was already sort of a been there done that thing, even if it was pretty good.
Compare Octavarium to Divine Wings, for instance. DWoT is a much more rigorous, complex, and satisfying song for me any day. Octavarium uses the whole "several pop songs strung together" thing for writing prog epics, which is fine (indeed the Odyssey is somewhat more like this too), it's just not really valid from where I'm standing to say they're more progressive than SX. And Count of Tuscany? Come on, that song was a train wreck.
I also don't like "spot the influence" prog, which DT does a lot of (oh look, ELP keys! Pink Floyd interlude! Instrumental mimicking Supper's Ready! Metallica riff! Kansas instrumental!) Has another band written something like Egypt or Church of the Machine? Maybe to some extent, but not really.