I presume that the accompanying 35mm audio mix would be taken from the 4.1 soundtrack from the BD
I've sampled some scenes from Jonno's brilliant BD of this pumping the PCM 2.0 through my amp and outputting it as DTS Neo 6 and your right, much better dynamic range, a bit more oompfh as well with the low ends.
I watched Alien on BD just before Prometheus came out and was a tad let down by the DTS-MA 5.1 mix. didn't have a lot of impact
I'm hoping when you've successfully ripped the 5.1 audio from the LD and synched it up to the 2010 BD, it should sound brilliant