I know HD audio isn't supported by makemkv because there are no players that support mkv and HD audio.
At the moment the only option to rip Blu-ray's on a mac is makemkv.
I have a network player (Popcorn Hour) that I use .ts files on with HD audio.
If makemkv could add HD audio I could rip all my Blu-ray's just using my mac and makemkv then run the file through tsmuxer.
No Windows PC required.