hairy_hen, you definitely need to hear the HD audio of The Matrix compared to the original first release DVD, as they do sound very different to me. The punches when Neo is fighting Morpheus in the training program lack that extra loudness that I am hearing on the AC3 mix. I am not sure why this is, but others have heard it too.

As for Batman, I haven't heard the Batman and Batman Returns earlier releases, but I can definitely say Batman Forever is different in nearly each release. The bit I like to listen to is when Batman is swinging from beneath the Chopper through Gotham.