I agree with much of that, but if he already has hairy_hen's 5.1 in DTS-HD, then there is no reason to change that to DD 640k (and introducing even more loss in the reencoding process as well) since, as you said, it includes a core DTS file for backwards compatibility. I can't think of any time in the last decade I've been unable to playback DTS on anything; but even if there's a hardware limitation due to a very, very old receiver or the like, software playback is an option to take care of it and pass on something usable. Anyone who can't play DTS has (correctable) issues beyond what they should bug Harmy with.

(what I've learned today: BD is not stuck at DVD's DD bitrate limit of 448kbps, but instead tops out at 640kbps)