Those "dodgy" internet copies always include the DTS core and sometimes the full HD audio depending on the group. You can easily find the full untouched Blu-ray or Remux as well. I don't know how up to date you are on current goings but this isn't like in the past where the only copies available were people filming in the back of a movie theater. You can encode a Blu-ray with x264 that will look visually transparent for most movies at 8-13 Mbps. Some will need more, some less, but you can usually cut the file size in half with no perceived quality loss.
Oh, I know exactly what the current scene and P2P standards are. I just believe that if you are going to get something decent, get the best quality there is, and that is always the source, blu-ray, and not a rip.
I in Aus and only get 150GB a month at 10mbit/s (for $70/month) so that is another consideration to take into account. We don't have nearly as many streaming services as those in the US, many due to insane bandwidth prices and lack of current fiber network.
That aside, I'm the type of person that believes spending money into an entertainment field that I enjoy. Want that 4K content quicker? You have to show with your wallet that the consumers are ready. Downloading rips doesn't do it for this industry.