(Finally) watched the first of these tonight, Prisoner of Azkaban.

A few thoughts:
Great picture quality and a completely professional editing job.

I’m pretty sure the BD doesn’t have a stereo track and IIRC the deleted scenes are stereo, so I can completely understand why JJPotter went with a full downmix instead of trying to upmix the extra scenes.
I just don’t love the audio. I felt like I was moving the volume up and down a lot, and even through a DPLII tuner, I don’t recall hearing anything behind me. Maybe if I pushed it through two speakers it would have sounded better.
I think I’m going to sync some English subtitles in the future though.

I was ready to say something about the Whomping Willow catching the same bird twice with the deleted scene addition, but I recall a conversation with ADM, who said that officially that’s how they edited it. So if it’s wrong, it’s at least wrong officially.

Overal, I love it and I’m ready to toss ADM’s old DVD.

Edit: Wow, I completely forgot to mention the extra extra scenes. The Knight Bus spin was fun, but Sirius breaking into Griffindor Tower was so well done you wouldn’t know the scene was incomplete. ❤️ having that back in the movie.

Edit 2: Goblet of Fire - My opinion is the same. I did switch my AVR to 2-channel output and the volume was fine. The tracks don’t upmix well.