that's a fair comment. the point here is obviously, if I have 5.1 DTS, then there is no need for 5.1 Dolby Digital. However what I will say, as this is NOT a proper 5.1 DTS mix produced by a studio I wonder if there is any point. the sound is being created from an original PCM track so perhaps 5.1 DD is the way to go after all.

so, we have a choice.

1. 5.1 DTS, mono soundtrack, commentary track, motion menus, film
2. 5.1 DTS, PCM 2.0 sound, basic menus, film
4. half bitrate 5.1 DTS track, pcm 2.0 sound, mono soundtrack, commentary track, motion menus, film (theoretically possible based on my calculations, 1gb for dts, 1.3 pcm, 300 commentary, 300 mono, 5gb film, leaves 500 for menus. bear in mind for a half rate DTS track, that is still 200kbps higher than a full bitrate 5.1 dolby digital track. )
3. 5.1 Dolby Digital, PCM 2.0 sound, mono soundtrack, commentary track, motion menus, film

Update

don't forget, the official dvd from 2004 is only 5.5gb ish for the video file so that leaves 3gb of space for sound and menus. possible on a dual layer disc.