I watched Harmy's Despecialized V2.5 with the latest version of the 70mm recreation. My sound system (nothing fancy, just a basic Home Cinema in a Box) can't handle DTS-HD so I only listened to the DTS core.
That said, I think I noticed an improvement in some scenes compared to the previous version on V2.1 (or maybe it was my imagination, or the placebo effect).
Did you mention somewhere that Prologic II decoding is designed to match what a Dolby Stereo track would actually sound like in a theatre?
Love the dynamic range on this, especially the whole section from Ben's death to the falcon escaping.