I'm glad you asked Number 20. The hybrid mono mix is the soundtrack of the Defcol used as a base with the best parts from the mono mix and the 2004 mix interspersed. Here's the list of changes.

From the mono mix:

C3P0's "We've Stopped" line restored from the sandcrawler.
Aunt Beru's lines have been reinstated.
Stormtrooper's "Allright, check that side of the street..." restored.
C3P0's Tractor Beam Spiel restored
Stormtrooper's "Close the blast doors" restored
Luke's "Blast it Wedge where are you?" restored.

From the 2004 OT:
The stormtrooper's "There's no one here" line.
And one other which has slipped my mind for now.