I remember owning the R6 DVD's of the JP trilogy and it was reported that they were mastered directly from the DTS cinema tracks as well. they sunded very good compared to the R1 DVD i had at the time
I've just recieved a copy of the BD with this preserved DTS track on it. look forward to comparing it actually.
From i've heard so far (only a few mins of it) the amount of work that went into preserving the track is phenomal!!!