Nice summary Gene. I did want to point out one subtlety that I don't think was mentioned. When we first started getting Blu-Rays and HD-DVDs and Dolby Digital + was the encoding of some soundtracks on those early discs, it seemed to always be the case that we were typically getting a quality and bit-rate higher than Dolby Digital. That is not really the case in streaming from my experience. The reason that Netflix gives everything in surround sound in Dolby Digital +, is not because they are delivering to us this higher quality soundtrack like we would get on those early Blu-ray's. They are doing this because it is more efficient than Dolby Digital, as you mentioned. I'm pretty sure that most surround sound soundtracks are just a Dolby Digital soundtrack, but in this more efficient encoding to get the bit-rate down. But, when Netflix puts out their original content, they make sure that the video and audio quality are as good as it gets, so I'm sure that they take advantage of the extra bit rate allowed by Dolby Digital + to give us a better soundtrack.
This seems to be how most other big steaming companies handle things as well, saving bandwidth going with Dolby Digital + and not increasing the quality. However, Vudu is the exception, they regularly give out higher quality audio when streaming, actually using more of that additional bit-rate in Dolby Digital +.