> I also felt that the mix of beautiful custom ambient music with the worn-out OM tracks didn’t always work
For me the music is what forced me to give this 7 instead of 8. It was simply too loud, omnipresent and drowned out the game sounds to the point of making you want to blackjack everything.
As for your last point I had the opposite experience, the maps in M4 gave you nearly perfect information. I agree it was visually intimidating due to darkness and verticality, but navigation certainly wasn't a problem (or maybe I misunderstood your point). I completely agree it was needlessly large and dragged towards the end.
I would recommend Lingering Whispers (from a quick glance it seems you haven't played it), the gameplay is quite compact and puzzle based. You could easily spend an hour on the puzzles alone.
Another one is The Dragon's Claw, most players get annoyingly stuck within couple minutes I think (me included). Just be aware to make some hard saves in the first mission, one of the puzzles can get bugged.
Both missions are actually high tier and visually appealing, but definitely not for everyon...