I think most actual DD 5.1 mixes on DVD are at 448kbps. Many are also at 384. Warner used 384 for most all titles up until a year or two ago. Usually it's the dolby 2.0 mixes that are 192kbps.

Dolby digital on LD was 384. So theoretically, the Star wars episode I dvd at 448 should be better than the lasers 384, but it's not the case.

Another one is Saving private Ryan. I had the DD DVD at one point, which was 448. Then I got the DTS DVD, which was 754, and it was loads better than the DD DVD. Then I got the DD laserdisc at 384 and it beats the pants off of them all. It is to this day the most intense soundtrack I've heard.

DTS on laserdisc was 1235kbps. DTS DVD started out at 1536kbps but was then cut in half to 754 to save space.