Encoding is part of mastering of the disc, you have to compress those big movies to fit onto 50 GB with more extras than most people care about. You said Sirius Pixels was the best, I just provided 3 examples of where it failed with a very large bitrate size. I have a couple of custom Blu-ray discs mastered from DCP with x264 configured properly and the results are quite stunning compared to their retail releases. They also playback fine on a number of Blu-ray players. At the end of the day, most of those commercial encoders do not provide nearly the range of customization that x264 does, and they also aren’t updated as consistently being that they are closed source. By the way, it’s 2016. And the films I listed were on the front page of Sirius Pixels website as “excellent Blu-ray encodes” released in 2015.