Gotta make this quick, but what Quantum Logic laid bare for me was the limitations of 2 channel. I've included the block chart provided by Harman at the demo. In my understanding, their are two basic advancements:
1) The ability to ID and extract all the 'streams' in space. This was demoed by taking Sinatra's voice out of a recording, playing just his voice, and then playing just the reverb from his voice. Presumably this can be done w/individual instruments too. A recording is analyzed in 'slices' from left to right, IDing all the components of the whole. Note that extractions are constantly being compared to the original signal.
2) The analysis and reconstruction of the signal into a '3D' entity that incorporates and distributes to the 12 channels ( 5 at roughly ear level as we're used to, then center height, 2x side height, 2x rear height) and the subs.
With that array of speakers (they called it 7.5.2), and the ability to, say, ID, a back wall reflection, ceiling reflection etc., and then route that through the proper speakers, you can recreate the event in a much more convincing way. This figures in RC to take your room out of the picture somewhat, and the venue reverb is now being directly radiated at you from the right locations. The reverb/ambience of the venue is arriving before the reverb/ambience of your room. The height and locations of all these recreates a 3D space in a way stereo can't.
The Shawn Colvin 2 channel track (recorded in a live venue) that was expanded into QL3D sounded tonally just like the stereo playback, only it put you into the venue so much more. The sound wasn't radiating just left/right of her sitting on stage, but in all directions like she's an omnidirectional point source. It was uncanny and disarming in how organic it sounded.
I owned a Lex MC12B which I didn't like much for music, but more to the point, found Logic 7 expansion just kinda fun for trippy stuff like Pink Floyd. It was clearly an 'inorganic' presentation. QL3D is an entirely different thing. Different too from any existing surround format. If I was dubious about the worth of height channels before, not now.
They showed a clip from The Matrix for a soundtrack demo -- interesting, but not nearly the mind-blower music was. Obviously there are all kinds of questions, but if it can work well for a variety of two channel music, it's the only truly new thing I've seen in awhile.