Great post, really helpful and mostly correct 
- DTS-HD MA is your friend, you don’t need HD compatible audio gear so long as your player is able to parse the stream and extract the DTS core. This can then be passed over ARC to your sound equipment
I strip the TrueHD streams from all my rips and use only AC3 (usually present alongside a TrueHD track) or DTS-HD MA tracks as I have a sound bar connected via ARC to my LG 4k set and that works just fine for me.
I’d also add something about subtitles to your piece. I can only speak with experience of the app on LG TVs, but PGS subs will always trigger a transcode as bitmap format needs burning in to the video stream. SRT subs can be streamed separately to the video and audio and overlaid by the client, and do not trigger a transcode.
