Whilst it would be nice to have a menu driven BD with extras, I personally would much rather have an mkv of the movie with a single lossless soundtrack and all other soundtracks downloadable separately so that I can mux them in as required without having to download more than I need.
In the fullness of time, when Harmy releases the full BD, perhaps he can make available the Bluray structure and supplementary files so that I can simply shoehorn the mkv (converted to m2ts) to match.
I also think any extras should be released on a "bonus" disc.
HD-DVD had a really great feature that allowed external subtitles and even soundtracks to be incorporated into the movie on the primary disc, without them having to be on the primary disc. I really miss that flexibility with Bluray.
I certainly wish Harmy the best in tackling the weird and wonderful world of Bluray authoring.