I see no evidence that suggests that subpar/dupey elements were used for StudioCanal's recent restoration. I see some lazy colour grading, sure, causing brightness to be matched inconsistently between shots in outdoor scenes, but nothing that suggests inferior elements were used compared to the old Criterion transfer.
Audio-wise, it's certainly the least tampered-with edition released to date. High frequencies haven't been attenuated at all, so everything sounds less muffled and boxy. Thin and tinny, yes, but that's just how the movie sounds.
As for the difference in dynamics, I believe some scenes were made louder in the old transfer; the new one doesn't appear to be compressed.
