"DTS is superior to DD"
Generally true. Llike all generalizations, not entirely true.
There are some DD tracks that are better than their DTS counterparts. Haven't documented them, but I've found several in my collection. Other collectors have similar findings. Hope they can help identify the DVDs.
On another note, the earlier DTS-only versions of some DVDs are reportedly superior to those with mixed (DTS and DD) soundtracks. Among the DTS-only ones were Dances with Wolves, Out of Sight, Saving Private Ryan. Those discs used the DTS capabilities better than those that had to devote more space to mixed tracks. Maybe someone can confirm this statement.